[ARM] 4158/1: Fix user page protection macros

The PAGE_* user page protection macros don't take into account the
configured memory policy and other architecture specific bits like
the global/ASID and shared mapping bits. Instead of constants let
these depend on a variable fixed up at init just like PAGE_KERNEL.

Signed-off-by: Imre Deak <imre.deak@solidboot.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>