KVM: arm64: Fix hyp_cpu_pm_{init,exit} __init annotation

The __init annotations on hyp_cpu_pm_{init,exit} are obviously incorrect,
and the build system shouts at you if you enable DEBUG_SECTION_MISMATCH.

Nothing really bad happens as we never execute that code outside of the
init context, but we can't label the callers as __int either, as kvm_init
isn't __init itself. Oh well.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20201223120854.255347-1-maz@kernel.org