ANDROID: KVM: arm64: Use hyp_alloc for pKVM VM hyp structures

Allocate the pKVM hypervisor internal structures using hyp_alloc(). This
streamlines host donations and acts like a cache for later allocations
which can lead to a faster VM creation.

Bug: 278749606
Bug: 273748186
Change-Id: I8df82c76fd837d5426021edd882f72df17174f2e
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>