COIL: Rename local variables in common i2c_controller
COIL: Rename local variables in common i2c_controller

Rename local variables and related comments in common i2c_controller
code.

BRANCH=None
BUG=None
TEST=make -j buildall

Signed-off-by: Diana Z <cb2016afc7183e5356c690dc63b4ba817470501a@chromium.org>
Change-Id: I712217d86f7232f509f1f649b772ec73204ceb53
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2558906
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>

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