ctr_el0 access is privileged on this platform and fails as an illegal
instruction.

Windows does not offer a way to flush data cache from userspace, and
only FlushInstructionCache is available in Windows API.

The generic implementation of flush_idcache_range uses,
__builtin___clear_cache, which already use the FlushInstructionCache
function. So we rely on that.

Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230221153006.20300-2-pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>