bloblist: add API to check the register conventions

Add bloblist_check_reg_conv() to check whether the bloblist is compliant
to the register conventions defined in Firmware Handoff specification.
This API can be used for all Arm platforms.

Signed-off-by: Raymond Mao <raymond.mao@linaro.org>

common/bloblist.c

@@ -542,3 +542,14 @@ int bloblist_maybe_init(void)
 
 	return 0;
 }
+
+int bloblist_check_reg_conv(ulong rfdt, ulong rzero, ulong rsig)
+{
+	if (rzero || rsig != (BLOBLIST_MAGIC | BLOBLIST_REGCONV_VER) ||
+	    rfdt != (ulong)bloblist_find(BLOBLISTT_CONTROL_FDT, 0)) {
+		gd->bloblist = NULL;  /* Reset the gd bloblist pointer */
+		return -EIO;
+	}
+
+	return 0;
+}