mb/google/rex: Add DRIVERS_GENESYSLOGIC_GL9755

Rex uses GL9755 and miss select the driver.

BUG=b:273906526
TEST=SD card is functional.

Signed-off-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Change-Id: I674b052689c80873e8a3b295d15788f3a93f0b82
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73760
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Ivy Jian <ivy.jian@quanta.corp-partner.google.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Subrata Banik <subratabanik@google.com>
diff --git a/src/mainboard/google/rex/Kconfig.name b/src/mainboard/google/rex/Kconfig.name
index d74c499..8216cc9 100644
--- a/src/mainboard/google/rex/Kconfig.name
+++ b/src/mainboard/google/rex/Kconfig.name
@@ -2,3 +2,4 @@
 
 config BOARD_GOOGLE_REX0
 	bool "-> Rex 0"
+	select DRIVERS_GENESYSLOGIC_GL9755