platform/x86: amd-pmc: Validate entry into the deepest state on resume

Currently the only way to discover if a system went into the deepest sleep
state is to read from sysfs after you finished suspend.

To better illustrate to users that problems have occurred, check as part
of resume and display a warning.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20220310150920.560583-1-mario.limonciello@amd.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>