avr32: fix copy_from_user()

commit 8630c322 upstream.

really ugly, but apparently avr32 compilers turns access_ok() into
something so bad that they want it in assembler.  Left that way,
zeroing added in inline wrapper.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>