Wire up the generic support for exposing CPU feature bits via the
modalias in /sys/device/system/cpu. This allows udev to automatically
load modules for things like crypto algorithms that are implemented
using optional instructions.

Since it is non-trivial to transparantly support both HWCAP and HWCAP2
capabilities in the cpu_feature() macro (which allows a module's hwcap
dependency and init routine to be declared using a single invocation of
module_cpu_feature_match()), support only HWCAP2 for now, which covers
the capabilities that are most likely to be useful in this manner.
Module dependencies on HWCAP will need to be declared explicitly via a
MODULE_DEVICE_TABLE(cpu, ...) declaration.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>