ft2232_spi: Revise comments about output pin states

The meaning of the variables is easy to misunderstand as some
states are merely implicit: All output pins that are not set
in the `cs_bits` mask will be constantly driven low. This may
be sheer coincidence as all programmers that need additional
pins driven use active-low signals to enable buffers.

While other pins stay low, *all* pins set in the `cs_bits`
mask are supposed to be toggled during SPI transactions.

Also drop some irritating dead code and try to explain things
in a comment.

Change-Id: I2b84ede01759c80f69d5ad17e43783d09ecd1107
Signed-off-by: Nico Huber <nico.h@gmx.de>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/55695
Original-Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71393
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
1 file changed