arm64: cpufeature: Set the FP/SIMD compat HWCAP bits properly

stable inclusion
from linux-4.19.105
commit b7230b62fc07902de0108d763b325f29eae3ead4

--------------------------------

commit 7559950a upstream

We set the compat_elf_hwcap bits unconditionally on arm64 to
include the VFP and NEON support. However, the FP/SIMD unit
is optional on Arm v8 and thus could be missing. We already
handle this properly in the kernel, but still advertise to
the COMPAT applications that the VFP is available. Fix this
to make sure we only advertise when we really have them.

Cc: stable@vger.kernel.org # v4.19
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Conflicts:
  arch/arm64/kernel/cpufeature.c
[yyl: replace CONFIG_COMPAT with CONFIG_AARCH32_EL0]
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>