[SCSI] tgt: fix undefined flush_dcache_page() problem

drivers/scsi/scsi_tgt_if.c: In function 'tgt_uspace_send_event':
drivers/scsi/scsi_tgt_if.c:88: warning: implicit declaration of function 'flush_dcache_page'

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>