platform/x86/intel/tpmi/plr: Make the file domain<n>/status writeable

platform/x86/intel/tpmi/plr: Make the file domain<n>/status writeable

The file sys/kernel/debug/tpmi-<n>/plr/domain<n>/status has store and show
callbacks. Make it writeable.

Fixes: 811f67c51636d ("platform/x86/intel/tpmi: Add new auxiliary driver for performance limits")
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Link: https://patch.msgid.link/20260127-plr-debugfs-write-v1-1-1fffbc370b1e@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>