ARM: 7840/1: LPAE: don't reject mapping /dev/mem above 4GB

ARM: 7840/1: LPAE: don't reject mapping /dev/mem above 4GB

With LPAE enabled, physical address space is larger than 4GB. Allow mapping any
part of it via /dev/mem by using PHYS_MASK to determine valid range.

PHYS_MASK covers 40 bits with LPAE enabled and 32 bits otherwise.

Bug 1474982

Reported-by: Vassili Karpov <av1474@comtv.ru>
Signed-off-by: Sergey Dyasly <dserrg@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
(cherry picked from commit 3159f372354e8e1f5dee714663d705dd2c7e0759)

Change-Id: I37133a68642b5856c358486bddacc7c4383ea812
Signed-off-by: Sami Kiminki <skiminki@nvidia.com>
Reviewed-on: http://git-master/r/417795
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>