x86: Fix movq immediate operand constraints in uaccess.h

The movq instruction, generated by __put_user_asm() when used for
64-bit data, takes a sign-extended immediate ("e") not a zero-extended
immediate ("Z").

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: stable@kernel.org