scsi: aic7xxx: Use kmemdup() in two places

kmemdup() can be used instead of kmalloc()+memcpy(). Replace two
occurrences of this pattern.

Issue identified with Coccinelle.

Link: https://lore.kernel.org/r/20200909185855.151964-1-alex.dewar90@gmail.com
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>