Add BoardPlatVendorPolicy to soong config

Bug: 205924657
Test: build
Change-Id: Ia0fe4fd916e539ee04aa0e8343068cc03bd9787c

android/config.go

@@ -1476,6 +1476,10 @@ func (c *deviceConfig) BoardSepolicyVers() string {
 	return c.PlatformSepolicyVersion()
 }
 
+func (c *deviceConfig) BoardPlatVendorPolicy() []string {
+	return c.config.productVariables.BoardPlatVendorPolicy
+}
+
 func (c *deviceConfig) BoardReqdMaskPolicy() []string {
 	return c.config.productVariables.BoardReqdMaskPolicy
 }