stm32: fix race condition in I2C response
stm32: fix race condition in I2C response

When we are transmitting a response to the EC, we don't want to race
with the TX empty interrupt handler. So just disable I2C interrupt
during the transmission.

Signed-off-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

BUG=None
TEST=on Lucas DVT, use the keyboard and see we are no longer getting
"bad checksum" in the kernel log.

Change-Id: Ic59532d1ac0a3eabb67ba0d498940986282bd87f
Reviewed-on: https://gerrit.chromium.org/gerrit/26162
Commit-Ready: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>
Tested-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

fourier49/BZ_DEV_EC,gelraen/cros-ec,fourier49/BIZ_EC,coreboot/chrome-ec,coreboot/chrome-ec,thehobn/ec,coreboot/chrome-ec,fourier49/BZ_DEV_EC,akappy7/ChromeOS_EC_LED_Diagnostics,thehobn/ec,coreboot/chrome-ec,longsleep/ec,longsleep/ec,fourier49/BZ_DEV_EC,gelraen/cros-ec,alterapraxisptyltd/chromium-ec,mtk09422/chromiumos-platform-ec,longsleep/ec,alterapraxisptyltd/chromium-ec,gelraen/cros-ec,alterapraxisptyltd/chromium-ec,mtk09422/chromiumos-platform-ec,thehobn/ec,gelraen/cros-ec,md5555/ec,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,alterapraxisptyltd/chromium-ec,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BIZ_EC,akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,fourier49/BIZ_EC,mtk09422/chromiumos-platform-ec,eatbyte/chromium-ec,eatbyte/chromium-ec,fourier49/BIZ_EC,fourier49/BZ_DEV_EC,thehobn/ec,coreboot/chrome-ec,md5555/ec,longsleep/ec,eatbyte/chromium-ec,mtk09422/chromiumos-platform-ec,md5555/ec,eatbyte/chromium-ec