kselftest/arm64: Handle attempts to disable SM on SME only systems

kselftest/arm64: Handle attempts to disable SM on SME only systems

The ABI for disabling streaming mode via ptrace is to do a write via the
SVE register set. Following the recent round of fixes to the ptrace code
we don't support this operation on systems without SVE, which is detected
as failures by fp-ptrace. Update the program so that it knows that this
operation is not currently supported.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250718-arm64-fp-ptrace-sme-only-v1-3-3b96dd19a503@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>