powerpc: kgdb: fix kernel-doc warnings

powerpc: kgdb: fix kernel-doc warnings

Remove empty comment line at the beginning of a kernel-doc function
block. Add a "Return:" section for this function.

These changes prevent 2 kernel-doc warnings:

Warning: ../arch/powerpc/kernel/kgdb.c:103 Cannot find identifier on line:
 *
Warning: kgdb.c:113 No description found for return value of 'kgdb_skipexception'

Fixes: 949616cf2d30 ("powerpc/kgdb: Bail out of KGDB when we've been triggered")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260225055314.247966-1-rdunlap@infradead.org