MIPS: BCM47XX: use common error codes in nvram reads

Instead of using our own error codes use some common codes.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: http://patchwork.linux-mips.org/patch/4739/
Signed-off-by: John Crispin <blogic@openwrt.org>
diff --git a/arch/mips/bcm47xx/sprom.c b/arch/mips/bcm47xx/sprom.c
index 289cc0a..66b71c3 100644
--- a/arch/mips/bcm47xx/sprom.c
+++ b/arch/mips/bcm47xx/sprom.c
@@ -51,7 +51,7 @@
 	create_key(prefix, postfix, name, key, sizeof(key));
 
 	err = nvram_getenv(key, buf, len);
-	if (fallback && err == NVRAM_ERR_ENVNOTFOUND && prefix) {
+	if (fallback && err == -ENOENT && prefix) {
 		create_key(NULL, postfix, name, key, sizeof(key));
 		err = nvram_getenv(key, buf, len);
 	}