ANDROID: Fix compat hwcap reporting on asymmetric 32-bit SoCs

When support for asymmetric 32-bit SoCs is enabled on the kernel
command-line, system_supports_32bit_el0() will always return true since
a late-onlined CPU could introduce the need for 32-bit support.

In order to avoid checking for the presence of compat hwcaps on
64-bit-only CPUs, adjust the verification of compat hwcaps for
late-onlined CPUs so that it is only performed for CPUs which actually
have 32-bit support. This allows late CPU hotplug of 64-bit-only CPUs on
a mismatched system. When mismatched support is not enabled,
incompatible CPUs are preventing from coming online by the CPU
capability.

Bug: 186482502
Change-Id: I22c285a54dbf9abb1a35e2bb608e5a41517f0ad0
Signed-off-by: Will Deacon <willdeacon@google.com>