nfs-utils: fix protocol minor version fall-back

nfs-utils: fix protocol minor version fall-back

Mount nfs directory would fail if no specific nfsvers:
mount -t nfs IP:/foo/bar/ /mnt/
mount.nfs: an incorrect mount option was specified

mount.nfs currently expects mount(2) to fail with EPROTONOSUPPORT if
the kernel doesn't understand the requested NFS version.
Unfortunately if the requested minor is not known to the kernel
it returns -EINVAL.

Backport patch from nfs-utils-1.3.4 to fix this issue.

Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>