xfs: rename xfs_attr_fetch to xfs_attr_get_int

Using a totally different name for the low-level get operation does
not fit the _int convention used in the rest of the attr code, so
rename it.

While we're at it also fix the prototype to use the normal convention
and mark it static as it's never used outside of xfs_attr.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Alex Elder <aelder@sgi.com>