ARM: uaccess: integrate uaccess_save and uaccess_restore

[ Upstream commit 8ede890b ]

Integrate uaccess_save / uaccess_restore macros into the new
uaccess_entry / uaccess_exit macros respectively.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>