KVM: arm64: Remove kvm_arch_vcpu_run_map_fp()

KVM: arm64: Remove kvm_arch_vcpu_run_map_fp()

Historically KVM hyp code saved the host's FPSIMD state into the hosts's
fpsimd_state memory, and so it was necessary to map this into the hyp
Stage-1 mappings before running a vCPU.

This is no longer necessary as of commits:

* fbc7e61195e2 ("KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state")
* 8eca7f6d5100 ("KVM: arm64: Remove host FPSIMD saving for non-protected KVM")

Since those commits, we eagerly save the host's FPSIMD state before
calling into hyp to run a vCPU, and hyp code never reads nor writes the
host's fpsimd_state memory. There's no longer any need to map the host's
fpsimd_state memory into the hyp Stage-1, and kvm_arch_vcpu_run_map_fp()
is unnecessary but benign.

Remove kvm_arch_vcpu_run_map_fp(). Currently there is no code to perform
a corresponding unmap, and we never mapped the host's SVE or SME state
into the hyp Stage-1, so no other code needs to be removed.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Will Deacon <will@kernel.org>
Cc: kvmarm@lists.linux.dev
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20250619134817.4075340-1-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>