intel_idle: Provide the default enter_dead() handler

Recent Intel platforms require idle driver to provide information about
the MWAIT hint used to enter the deepest idle state in the play_dead
code.

Provide the default enter_dead() handler for all of the platforms and
allow overwriting with a custom handler for each platform if needed.

Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/all/20250205155211.329780-4-artem.bityutskiy%40linux.intel.com