KVM: arm64: Simplify visibility handling of AArch32 SPSR_*

Since SPSR_* are not associated with any register in the sysreg array,
nor do they have .get_user()/.set_user() helpers, they are invisible to
userspace with that encoding.

Therefore hidden_user_visibility() serves no purpose here, and can be
safely removed.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240904082419.1982402-3-maz@kernel.org


Signed-off-by: Marc Zyngier <maz@kernel.org>