Fix the following out-of-bounds warnings by embedding existing struct
htb_rel_query into struct mpt3_addnl_diag_query, instead of duplicating its
members:

include/linux/fortify-string.h:20:29: warning: '__builtin_memcpy' offset [19, 32] from the object at 'karg' is out of the bounds of referenced subobject 'buffer_rel_condition' with type 'short unsigned int' at offset 16 [-Warray-bounds]
include/linux/fortify-string.h:22:29: warning: '__builtin_memset' offset [19, 32] from the object at 'karg' is out of the bounds of referenced subobject 'buffer_rel_condition' with type 'short unsigned int' at offset 16 [-Warray-bounds]

The problem is that the original code is trying to copy data into a bunch
of struct members adjacent to each other in a single call to memcpy(). All
those members are exactly the same contained in struct htb_rel_query, so
instead of duplicating them into struct mpt3_addnl_diag_query, replace them
with new member rel_query of type struct htb_rel_query. So, now that this
new object is introduced, memcpy() doesn't overrun the length of
&karg.buffer_rel_condition, because the address of the new struct object
_rel_query_ is used as destination, instead. The same issue is present when
calling memset(), and it is fixed with this same approach.

Below is a comparison of struct mpt3_addnl_diag_query, before and after
this change (the size and cachelines remain the same):

$ pahole -C mpt3_addnl_diag_query drivers/scsi/mpt3sas/mpt3sas_ctl.o
struct mpt3_addnl_diag_query {
	struct mpt3_ioctl_header   hdr;                  /*     0    12 */
	uint32_t                   unique_id;            /*    12     4 */
	uint16_t                   buffer_rel_condition; /*    16     2 */
	uint16_t                   reserved1;            /*    18     2 */
	uint32_t                   trigger_type;         /*    20     4 */
	uint32_t                   trigger_info_dwords[2]; /*    24     8 */
	uint32_t                   reserved2[2];         /*    32     8 */

	/* size: 40, cachelines: 1, members: 7 */
	/* last cacheline: 40 bytes */
};

$ pahole -C mpt3_addnl_diag_query drivers/scsi/mpt3sas/mpt3sas_ctl.o
struct mpt3_addnl_diag_query {
	struct mpt3_ioctl_header   hdr;                  /*     0    12 */
	uint32_t                   unique_id;            /*    12     4 */
	struct htb_rel_query       rel_query;            /*    16    16 */
	uint32_t                   reserved2[2];         /*    32     8 */

	/* size: 40, cachelines: 1, members: 4 */
	/* last cacheline: 40 bytes */
};

Also, this helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines on
memcpy().

Link: https://github.com/KSPP/linux/issues/109
Link: https://lore.kernel.org/lkml/60659889.bJJILx2THu3hlpxW%25lkp@intel.com/
Link: https://lore.kernel.org/r/20210401162054.GA397186@embeddedorBuild-tested-by: kernel test robot <lkp@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>