scsi: aacraid: Make some symbols static in aachba.c

This eliminates the following sparse warning:

drivers/scsi/aacraid/aachba.c:245:5: warning: symbol 'aac_convert_sgl'
was not declared. Should it be static?
drivers/scsi/aacraid/aachba.c:293:5: warning: symbol 'acbsize' was not
declared. Should it be static?
drivers/scsi/aacraid/aachba.c:324:5: warning: symbol 'aac_wwn' was not
declared. Should it be static?

Link: https://lore.kernel.org/r/20200912033749.142488-1-yanaijie@huawei.com
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>