platform/chrome: kunit: cros_ec_i2c: Add tests with kprobe stub

For running the tests:

$ ./tools/testing/kunit/kunit.py run \
        --arch=x86_64 \
        --kconfig_add CONFIG_KPROBES=y \
        --kconfig_add CONFIG_KUNIT_KPROBE_STUBS=y \
        --kconfig_add CONFIG_CHROME_PLATFORMS=y \
        --kconfig_add CONFIG_CROS_EC=y \
        --kconfig_add CONFIG_I2C=y \
        --kconfig_add CONFIG_CROS_EC_I2C=y \
        --kconfig_add CONFIG_CROS_KUNIT_EC_I2C_TEST=y \
        cros_ec_i2c*

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>