KVM: PPC: Book3S HV: remove unused kvmppc_h_protect argument

The va argument is not used in the function or set by its asm caller,
so remove it to be safe.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412014845.1517916-8-npiggin@gmail.com