Cr50: i2cs: Added counter for write mismatch error
Cr50: i2cs: Added counter for write mismatch error

During TPM I2CS stress testing as described in chrome-os-partner:59191
there were instances of write mismatch errors. Previously, there was a
CPRINTF for this condition. The CPRINTF being in the i2cs ISR then
affects any subsequent i2cs activity and can create a cascade of
errors.

To avoid this issue, added a counter to track these instances and made
it to be retrieved similar to the fifo adjust counter.

BRANCH=none
BUG=chrome-os-partner:57338,chrome-os-partner:59191
TEST=manual
Ran the stress test as described in chrome-os-partner:59191 and found
that when the write mismatch occurred the counter ticked up by 2 where
before there would be numerous console log prints of the same error.

Change-Id: I2837d02037e2f47b5bd4b001d3394ad6eb4bd92c
Signed-off-by: Scott <7d40b3eb9e17bf55d972074a5e77a7ea4159f9dd@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/410032
Commit-Ready: Scott Collyer <7d40b3eb9e17bf55d972074a5e77a7ea4159f9dd@chromium.org>
Tested-by: Scott Collyer <7d40b3eb9e17bf55d972074a5e77a7ea4159f9dd@chromium.org>
Reviewed-by: Vadim Bendebury <5515d6d2d0829cbe0dd0dcf2094aaded06d58514@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec