[SCSI] aacraid: linit.c make aac_show_serial_number static

drivers/scsi/aacraid/linit.c:865:9: warning: symbol 'aac_show_serial_number' was not declared. Should it be static?

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Mark Salyzyn <Mark_Salyzyn@adaptec.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>