gsmd: Use /dev/ttyS2 on sysmobts v2

only the first prototype board (on the v2B mainboard) was using ttyS0, messing
up console access.  This has been fixed in v2.x of the db9 daughterboard for
the v2C mainboards.
diff --git a/recipes-openmoko/openmoko-gsmd/files/default b/recipes-openmoko/openmoko-gsmd/files/default
index e7c536b..766b389 100644
--- a/recipes-openmoko/openmoko-gsmd/files/default
+++ b/recipes-openmoko/openmoko-gsmd/files/default
@@ -37,7 +37,7 @@
                 ;;
 	"sysmocom_sysmobts_v2")
 		GSMD_OPTS="-v wavecom"
-		GSM_DEV="/dev/ttyS0"
+		GSM_DEV="/dev/ttyS2"
 		;;
 	*)
 		# Unknown board