ANDROID: KVM: arm64: Allow loading modules to the pKVM hypervisor

All nVHE hypervisor code is currently required to be statically linked
into the kernel image. Sadly, scaling pKVM will inevitably require
running _some_ hardware-specific code in the hypervisor due to the
absence of architecture requirements regarding IOMMU implementations or
power management, for example.

In order to address this issue, introduce the ability to load modules
in the pKVM hypervisor at run-time. pKVM modules are expected to be
embedded inside kernel modules, and to be loaded into pKVM when their
kernel counterpart is loaded at EL1. pKVM module loading is defined as a
privileged operation -- all of them must be loaded while the host kernel
is still part of the trusted computing base.

Bug: 278749606
Bug: 244543039
Bug: 244373730
Co-authored-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Change-Id: If8e5d3ac0a2893c892aff09e5b51d3b8e14693f8
Signed-off-by: Quentin Perret <qperret@google.com>