drivers/storage: Make DRVR_CAP_8BIT controller independent

Promote DRVR_CAP_8BIT from controller specific to controller independent

TEST=Build and run on Galileo Gen2

Change-Id: I51e4c990d3941a9f31915a5703095f92309760f1
Signed-off-by: Lee Leahy <Leroy.P.Leahy@intel.com>
Reviewed-on: https://review.coreboot.org/19642
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
2 files changed