alpha: switch __copy_user() and __do_clean_user() to normal calling conventions

commit 8525023121de4848b5f0a7d867ffeadbc477774d upstream.

They used to need odd calling conventions due to old exception handling
mechanism, the last remnants of which had disappeared back in 2002.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>