mb/google/rex: Use GPP_C15 as WWAN_DPR_SAR_ODL

BUG=b:263413949
TEST=Able to build and boot Google/Rex.

Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: I453fe8e1f4b4b8d4730ade259899d76aec949a44
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71231
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
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>
diff --git a/src/mainboard/google/rex/variants/rex0/gpio.c b/src/mainboard/google/rex/variants/rex0/gpio.c
index 128fd32..7e04869 100644
--- a/src/mainboard/google/rex/variants/rex0/gpio.c
+++ b/src/mainboard/google/rex/variants/rex0/gpio.c
@@ -135,8 +135,8 @@
 	PAD_CFG_NF(GPP_C12, NONE, DEEP, NF1),
 	/* GPP_C13 : [] ==> SSD_CLKREQ_ODL */
 	PAD_CFG_NF(GPP_C13, NONE, DEEP, NF1),
-	/* GPP_C15 : [] ==> GPP_C15_STRAP */
-	PAD_NC(GPP_C15, NONE),
+	/* GPP_C15 : [] ==> WWAN_DPR_SAR_ODL */
+	PAD_CFG_GPO(GPP_C15, 1, DEEP),
 	/* GPP_C16 : [] ==> USB_C0_LSX_TX */
 	PAD_CFG_NF(GPP_C16, NONE, DEEP, NF1),
 	/* GPP_C17 : [] ==> USB_C0_LSX_RX */