nouveau_acpi: convert acpi_get_handle() to acpi_has_method()

nouveau_acpi: convert acpi_get_handle() to acpi_has_method()

commit 187b5b5d520c2318a1f88fb8d8913a9d7fbf7d92 upstream.

acpi_has_method() is a new ACPI API introduced to check
the existence of an ACPI control method.

It can be used to replace acpi_get_handle() in the case that
1. the calling function doesn't need the ACPI handle of the control method.
and
2. the calling function doesn't care the reason why the method is unavailable.

Convert acpi_get_handle() to acpi_has_method()
in drivers/gpu/drm/nouveau/nouveau_acpi.c in this patch.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
CC: Ben Skeggs <bskeggs@redhat.com>
CC: Dave Airlie <airlied@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>