ACPI: scan: Do not mark button ACPI devices as wakeup-capable

ACPI: scan: Do not mark button ACPI devices as wakeup-capable

It is generally questionable to mark struct acpi_device "devices" as
wakeup-capable because they represent firmware entities that by
themselves have no wakeup capabilities.

It was done for struct acpi_device "devices" corresponding to buttons
because the ACPI button driver was binding to them directly, but now
that corresponding platform devices are created for the buttons and
they are marked as wakeup-capable by the ACPI button driver, there is
no reason to continue doing it.

Update acpi_wakeup_gpe_init() accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/2891119.BEx9A2HvPv@rafael.j.wysocki