RDMA: rdma_user_ioctl.h: fix a duplicated word + clarify

Change the repeated word "it" in a comment to "it to".
Also insert a dash in the sentence to add clarity.

Link: https://lore.kernel.org/r/20200719003220.21250-1-rdunlap@infradead.orgSigned-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

include/uapi/rdma/rdma_user_ioctl.h

@@ -43,7 +43,7 @@
 
 /*
  * General blocks assignments
- * It is closed on purpose do not expose it it user space
+ * It is closed on purpose - do not expose it to user space
  * #define MAD_CMD_BASE		0x00
  * #define HFI1_CMD_BAS		0xE0
  */