Define SPL for boot and vendor

In previous builds Qualcomm makefiles set the boot and vendor security
patch level. Make sure we do the same so that the properties that land
(among others) in vbmeta.img stay consistent.

Change-Id: Idf572404923a15b3a50256ecea7012693e26e13e
diff --git a/device.mk b/device.mk
index 5d7866e..406b1bb 100644
--- a/device.mk
+++ b/device.mk
@@ -52,6 +52,11 @@
 $(warning Build defined as $(BUILD_ID) ($(BUILD_NUMBER)))
 
 
+# Define SPL for boot & vendor
+BOOT_SECURITY_PATCH := $(PLATFORM_SECURITY_PATCH)
+VENDOR_SECURITY_PATCH := $(PLATFORM_SECURITY_PATCH)
+
+
 # We don't have the calibration data as this sort of
 # data can only be generated at the factory so don't generate persist.img
 FP3_SKIP_PERSIST_IMG := true