UPSTREAM: platform/chrome: cros_ec_proto: Allow to build as module

Allow to build ChromeOS EC communication protocol helpers as
kernel module which is particularly useful for Android GKI (Generic
Kernel Image) configuration. With this change the ChromeOS Platform
(CONFIG_CHROME_PLATFORMS=y) can be enabled directly from the vendor
kconfig fragment whithout additional configuration in gki_defconfig.

Bug: 447025659

Change-Id: I2d6840ea61029bcd5361f2234dc90294fa97b29a
Signed-off-by: Slawomir Rosek <srosek@chromium.org>
Link: https://lore.kernel.org/r/20250328132612.511471-1-srosek@chromium.org


Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
(cherry picked from commit ccf395bd)
Signed-off-by: Zyta Szpak <zyta@google.com>