KVM: arm64: Drop useless struct s2_mmu in __kvm_at_s1e2()

__kvm_at_s1e2() contains the definition of an s2_mmu for the
current context, but doesn't make any use of it. Drop it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241023145345.1613824-5-maz@kernel.org


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>