[PATCH] libata: init ap->cbl to ATA_CBL_SATA early

Init ap->cbl to ATA_CBL_SATA in ata_host_init().  This is necessary
for soon-to-follow SCR handling function changes.  LLDDs are free to
change ap->cbl during probing.

Signed-off-by: Tejun Heo <htejun@gmail.com>