ptp: ptp_clockmatrix: repair non-kernel-doc comment

Do not use "/**" to begin a comment that is not in kernel-doc format.

Prevents this docs build warning:

drivers/ptp/ptp_clockmatrix.c:1679: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * Maximum absolute value for write phase offset in picoseconds

Then remove the kernel-doc-like function parameter descriptions
since they don't add any useful info. (suggested by Jakub)

Fixes: 794c3dff ("ptp: ptp_clockmatrix: Add support for FW 5.2 (8A34005)")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Min Li <min.li.xe@renesas.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20211111155034.29153-1-rdunlap@infradead.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/ptp/ptp_clockmatrix.c

@@ -1699,12 +1699,9 @@ static int initialize_dco_operating_mode(struct idtcm_channel *channel)
 
 /* PTP Hardware Clock interface */
 
-/**
+/*
  * Maximum absolute value for write phase offset in picoseconds
  *
- * @channel:  channel
- * @delta_ns: delta in nanoseconds
- *
  * Destination signed register is 32-bit register in resolution of 50ps
  *
  * 0x7fffffff * 50 =  2147483647 * 50 = 107374182350