Adds a retry/faildown to SB600 SATA detection logic. SATA port status kept returning 0x1: BAR5+po+28h 1h = Device presence detected but Phy communication not established   This patch adds logic to force 1.5g if the drive fails to communicate at 3.0g. Thanks Dan Lykowski Signed-off-by: Dan Lykowski <lykowdk@gmail.com>