Change in flashrom[master]: bitbang-spi.c: support clock polarity and phase

[Xiang Wang (Code Review)]

Attention is currently required from: Xiang Wang, Stefan Reinauer, Angel Pons.
Hello build bot (Jenkins), Stefan Reinauer, Edward O'Callaghan, Angel Pons,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/flashrom/+/49255

to look at the new patch set (#13).

Change subject: bitbang-spi.c: support clock polarity and phase
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bitbang-spi.c: support clock polarity and phase

SPI has four modes, which are determined by Clock polarity and Clock phase. See
https://en.wikipedia.org/wiki/Serial_Peripheral_Interface#Clock_polarity_and...
for details. The previous code only supports one mode and may not be able to
handle some special spi flash. This patch uses spi's mode0 by default to
be consistent with the previous code.

TEST=build and run flashrom with sysfsgpio on raspberrypi to read  W25Q128.V

Change-Id: I04c1dfe132d756119229b27c3cd611d1be1abc8d
Signed-off-by: Xiang Wang 
---
M bitbang_spi.c
1 file changed, 70 insertions(+), 16 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/55/49255/13