ANDROID: KVM: arm64: Add helper for pKVM modules addr conversion

pKVM modules can't rely on the usual hyp function kern_hyp_va() to
convert addr from the kernel space to the hyp's. Instead, provide
pkvm_el2_mod_va() that will do the conversion using the token provided
by pkvm_load_el2_module().

Bug: 244543039
Bug: 244373730
Change-Id: I7423b40f1107bb92cd732843c5cdbf1d45662f00
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>