mvsas: fix misleading indentation

Fix a smatch warning:
drivers/scsi/mvsas/mv_sas.c:740 mvs_task_prep() warn: curly braces intended?

The code is correct, the indention is misleading. When the device is not
ready we want to return SAS_PHY_DOWN. But current indentation makes it
look like we only do so in the else branch of if (mvi_dev).

Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>