ACPI: platform_profile: Add concept of a "custom" profile

ACPI: platform_profile: Add concept of a "custom" profile

When two profile handlers don't agree on the current profile it's ambiguous
what to show to the legacy sysfs interface.

Add a "custom" profile string that userspace will be able to use the legacy
sysfs interface to distinguish this situation..

Additionally drivers can choose to use this to indicate that a user has
modified driver settings in a way that the platform profile advertised by
a driver is not accurate.

Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Tested-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Reviewed-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20241206031918.1537-17-mario.limonciello@amd.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>