Adding TARGET_OTA_ASSERT_DEVICE flag for custom device asserts

Should be handled via device tree's BoardConfig
Sample will be TARGET_OTA_ASSERT_DEVICE := le_zl1,zl1,lepro3,lex720,lex727,LEX720,LEX727 in BoardConfig
Only applicable for AB or VAB devices

Change-Id: I1fbe6155d3f79eee089a31dbe62ee9d04c33d65c
diff --git a/twrp.cpp b/twrp.cpp
index 564454a..c84c99e 100644
--- a/twrp.cpp
+++ b/twrp.cpp
@@ -377,6 +377,10 @@
 	property_set("ro.twrp.boot", "1");
 	property_set("ro.twrp.version", TW_VERSION_STR);
+	property_set("", TARGET_OTA_ASSERT_DEVICE);
 	time_t StartupTime = time(NULL);
 	printf("Starting TWRP %s-%s on %s (pid %d)\n", TW_VERSION_STR, TW_GIT_REVISION, ctime(&StartupTime), getpid());