mb/google/rex: Add ELAN6918 touchscreen

ELAN6918 Power Sequencing seems not perfectly matching
with the previous platforms and setting GPP_C06 to high prior
to the power sequencing is actually makes it work.

Ideally Power Sequencing should be as below for ELAN6918 (in ACPI)
`POWER enabled -> RESET deasserted -> Report EN enabled`

But below sequence is only working currently:
`Report EN enabled (ramstage) -> POWER enabled (ACPI) -> RESET
 deasserted (ACPI)`

BUG=b:247029304
TEST=Verified ELAN touch panel is working as expected after booting
Google/rex device to ChromeOS.

Change-Id: Ideaeb0faa882b8e603534bbface51ea76923d436
Signed-off-by: Eran Mitrani <mitrani@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66990
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tarun Tuli <taruntuli@google.com>
diff --git a/src/mainboard/google/rex/Kconfig b/src/mainboard/google/rex/Kconfig
index 43fe13d..bff688f 100644
--- a/src/mainboard/google/rex/Kconfig
+++ b/src/mainboard/google/rex/Kconfig
@@ -5,6 +5,7 @@
 	select BOARD_ROMSIZE_KB_65536
 	select DRIVERS_GENERIC_MAX98357A
 	select DRIVERS_I2C_GENERIC
+	select DRIVERS_I2C_HID
 	select DRIVERS_SOUNDWIRE_ALC5682
 	select DRIVERS_WIFI_GENERIC
 	select EC_GOOGLE_CHROMEEC