sb/intel/spi: Check for the SPI lock bit during runtime

sb/intel/spi: Check for the SPI lock bit during runtime

The SPI swseq controller can be locked in other parts of the code, for
instance when it's locked down in the finalize section. The driver
has to be made aware of that. The simpler solution is to not keep
track of the state and simply read out the lock bit on each SPI
transfer.

Change-Id: Ifcd5121b89d6f80fc1c1368786982d0d9fa1bf61
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33388
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>