PM: runtime: Simplify pm_runtime_get_if_active() usage

There are two ways to opportunistically increment a device's runtime PM
usage count, calling either pm_runtime_get_if_active() or
pm_runtime_get_if_in_use(). The former has an argument to tell whether to
ignore the usage count or not, and the latter simply calls the former with
ign_usage_count set to false. The other users that want to ignore the
usage_count will have to explicitly set that argument to true which is a
bit cumbersome.

To make this function more practical to use, remove the ign_usage_count
argument from the function. The main implementation is in a static
function called pm_runtime_get_conditional() and implementations of
pm_runtime_get_if_active() and pm_runtime_get_if_in_use() are moved to
runtime.c.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Takashi Iwai <tiwai@suse.de> # sound/
Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com> # drivers/accel/ivpu/
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com> # drivers/gpu/drm/i915/
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com> # drivers/pci/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>