Strictly speaking, stat() doesn't return a detailed error code as its
return value and it can and should be obtained via 'errno'.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>