KVM: arm64: Type-check hypercall arguments at the caller

kvm_call_hyp_nvhe() reduces its target to an SMCCC function number, so
the compiler never sees a callable: arguments that are wrong in number,
type or order are silently marshalled into registers. The kvm_call_hyp()
wrappers only catch this on the VHE branch, and the pKVM-only hypercalls
have no such branch.

Declare each hypercall's signature once in kvm_hcall.h and generate a
typed stub from it, in the mold of the syscall wrappers. Make
kvm_call_hyp_nvhe() resolve to the stub so every caller is checked
against the declared signature; a stale or mistyped call now fails to
compile. The stubs inline to the same SMCCC call the untyped macro used
to make: the compiled callers are unchanged, apart from hypercall
returns now being tested at their declared width.

The stage-2 protection arguments are declared u64 rather than
enum kvm_pgtable_prot, as kvm_pgtable.h includes linux/kvm_host.h and
the enum cannot be completed here.

Assisted-by: Antigravity:gemini-3.1-pro
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>