ARM: virt: simplify __hyp_stub_install epilog

ARM: virt: simplify __hyp_stub_install epilog

commit d01723479e6a6c70c83295f7847477a016d5e14a upstream.

__hyp_stub_install duplicates quite a bit of safe_svcmode_maskall
by forcing the CPU back to SVC. This is unnecessary, as
safe_svcmode_maskall is called just after.

Furthermore, the way we build SPSR_hyp is buggy as we fail to mask
the interrupts, leading to interesting behaviours on TC2 + UEFI.

The fix is to simply remove this code and rely on safe_svcmode_maskall
to do the right thing.

Reviewed-by: Dave Martin <dave.martin@linaro.org>
Reported-by: Harry Liebel <harry.liebel@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>