scsi: mpt3sas: Fix an outdated comment

May reduce confusion for users of MPI2_CONFIG_PAGE_IO_UNIT_3::GPIOVal[].

Fixes: a1c4d774 ("scsi: mpt3sas: Replace unnecessary dynamic allocation with a static one")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Seo <james@equiv.tech>
Link: https://lore.kernel.org/r/20230806170604.16143-10-james@equiv.tech


Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>