ARM: 8658/1: uaccess: fix zeroing of 64-bit get_user()

commit 9e3440481845b2ec22508f60837ee2cab2b6054f upstream.

The 64-bit get_user() wasn't clearing the high word due to a typo in the
error handler. The exception handler entry was already correct, though.
Noticed during recent usercopy test additions in lib/test_user_copy.c.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>