gta4xl: this is a single sim device

Change-Id: I135b1463eec7ae0e445583c744fdb006dd776464
diff --git a/vendor.prop b/vendor.prop
index bf980c8..b872ffa 100644
--- a/vendor.prop
+++ b/vendor.prop
@@ -1,3 +1,4 @@
 ### RIL
+ro.vendor.multisim.simslotcount=1
 vendor.rild.libpath=/vendor/lib64/libsec-ril.so
 vendor.sec.rild.libpath=/vendor/lib64/libsec-ril.so