soc: fsl: guts: check return value after calling of_iomap() in fsl_guts_get_soc_uid()

of_iomap() may return NULL, so we need check the return value.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/soc/fsl/guts.c

@@ -126,6 +126,10 @@ static u64 fsl_guts_get_soc_uid(const char *compat, unsigned int offset)
 		return 0;
 
 	sfp_base = of_iomap(np, 0);
+	if (!sfp_base) {
+		of_node_put(np);
+		return 0;
+	}
 
 	uid = ioread32(sfp_base + offset);
 	uid <<= 32;