platform/x86: intel: punit_ipc: Remove unused function

intel_punit_ipc_simple_command() was added in 2015 by
commit fdca4f16 ("platform:x86: add Intel P-Unit mailbox IPC driver")
but never used.

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://lore.kernel.org/r/20241221234807.160473-1-linux@treblig.org


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>