arm64/fpsimd: Remove unused fpsimd_force_sync_to_sve()

There have been no users of fpsimd_force_sync_to_sve() since commit:

  bbc6172e ("arm64/fpsimd: SME no longer requires SVE register state")

Remove fpsimd_force_sync_to_sve().

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20250409164010.3480271-3-mark.rutland@arm.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>