ACPI: DPTF: Fix participant driver names

Change the names of DPTF participant drivers to adhere to the
sysfs file naming conventions (no spaces present in the name in
particular).

Fixes: 2ce6324e ("ACPI: DPTF: Add PCH FIVR participant driver")
Fixes: 6256ebd5

 ("ACPI / DPTF: Add DPTF power participant driver")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Borislav Petkov <bp@suse.de>