scsi: target: core: file: Don't duplicate memset(0xff)

scsi: target: core: file: Don't duplicate memset(0xff)

The function fd_do_prot_fill() is called from two callers
fd_do_prot_unmap() and fd_format_prot(). Both callers initialize the passed
buffer to 0xff with memset().

Move the memset() call to fd_do_prot_fill() to avoid duplication.

Link: https://lore.kernel.org/r/20210228055645.22253-24-chaitanya.kulkarni@wdc.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>