openrisc: uaccess: Fix sparse address space warnings

The OpenRISC user access functions put_user(), get_user() and
clear_user() were missing proper sparse annotations.  This generated
warnings like the below.

This patch adds the annotations to fix the warnings.

Example warnings:

net/ipv4/ip_sockglue.c:759:29: warning: incorrect type in argument 1 (different address spaces)
net/ipv4/ip_sockglue.c:759:29:    expected void const volatile [noderef] __user *
net/ipv4/ip_sockglue.c:759:29:    got int const *__gu_addr
net/ipv4/ip_sockglue.c:764:29: warning: incorrect type in initializer (different address spaces)
net/ipv4/ip_sockglue.c:764:29:    expected unsigned char const *__gu_addr
net/ipv4/ip_sockglue.c:764:29:    got unsigned char [noderef] __user *

Signed-off-by: Stafford Horne <shorne@gmail.com>
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>