chip/nxcp/lpc: Fix race condition when reading 8042 data.
chip/nxcp/lpc: Fix race condition when reading 8042 data.

When reading NPCX_HIKMDI it deasserts the IBF status flag. This means
the AP is allowed to write to the input buffer. Because NPCX_HIKMDI is
read twice, that means the AP could have written to the input buffer
between reads. This results in losing one of the interrupts. This only
happens if DEBUG_LPC is enabled.

BUG=b:145575366
BRANCH=none
TEST=Verified we don't lose any writes by examining logs.

Change-Id: I2904c316fcad55001e8d297f4a0a73073b07702b
Signed-off-by: Raul E Rangel <9a9c998e11a2655b1de9a05eeeef5f710c0dc7ed@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2073280
Reviewed-by: Edward Hill <db1406b34e091703092b6b136bdfeb2c8125fc0e@chromium.org>

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