UPSTREAM: arm64: Handle faults caused by inadvertent user access with PAN enabled

When TTBR0_EL1 is set to the reserved page, an erroneous kernel access
to user space would generate a translation fault. This patch adds the
checks for the software-set PSR_PAN_BIT to emulate a permission fault
and report it accordingly.

Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Bug: 31432001
Change-Id: I87e48f6075f84878e4d26d4fadf6eaac49d2cb4e
(cherry picked from commit 786889636ad75296c213547d1ca656af4c59f390)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>