platform: msm_shared: Add platform subtype for PM660 support.

Add platform subtype for 8909 chip with PM660.

Change-Id: Ie77e0c2712efc6488318f61900e2defa44a6b535
diff --git a/platform/msm_shared/smem.h b/platform/msm_shared/smem.h
index bad142c..8e199c7 100644
--- a/platform/msm_shared/smem.h
+++ b/platform/msm_shared/smem.h
@@ -509,6 +509,7 @@
 	HW_PLATFORM_SUBTYPE_POLARIS = 64,
 	HW_PLATFORM_SUBTYPE_SWOC_WEAR = 9,
 	HW_PLATFORM_SUBTYPE_SWOC_NOWGR_CIRC = 13,
+	HW_PLATFORM_SUBTYPE_8909_PM660 = 15,
 	HW_PLATFORM_SUBTYPE_32BITS = 0x7FFFFFFF
 };