ACPI: sysfs: Allow bitmap list to be supplied to acpi_mask_gpe

Currently we need to use as many acpi_mask_gpe options as we want to have
GPEs to be masked. Even with two it already becomes inconveniently large
the kernel command line.

Instead, allow acpi_mask_gpe to represent bitmap list.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>