Return correct error number in ubi_get_vol_info1

Return correct error number in ubi_get_vol_info1

If the specified UBI device or volume does not exist, the function
is supposed to set errno to ENODEV.

This patch adds a check to ubi_get_vol_info1 to change the errno
to ENODEV if vol_get_major cannot access the underlying sysfs file,
so the function propperly returns that the device or volume does
not exist, instead of failing with errno set to ENOENT.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>