sdm: Add property to prefer multirect strategy

Define vendor.display.prefer_multirect to prefer multirect pipes while
assigning the pipes for each layer.

Change-Id: Ic0ec9dc3e1c9b26d0eb5114d319b1fd120ef4954
CRs-Fixed: 2142708
diff --git a/include/display_properties.h b/include/display_properties.h
index c321b98..ddcde64 100644
--- a/include/display_properties.h
+++ b/include/display_properties.h
@@ -106,6 +106,7 @@
 #define QDCM_DIAGONAL_MATRIXMODE_PROP        DISPLAY_PROP("qdcm.diagonal_matrix_mode")
 #define QDCM_DISABLE_TIMEOUT_PROP            PERSIST_DISPLAY_PROP("qdcm.disable_timeout")
 #define QDCM_MODE_COMBINE_PROP               DISPLAY_PROP("qdcm.mode_combine")
+#define PREFER_MULTIRECT_PROP                DISPLAY_PROP("prefer_multirect")
 
 #define ZERO_SWAP_INTERVAL                   "vendor.debug.egl.swapinterval"