phy: core: Discard pm_runtime_put() return values

The PHY core defines phy_pm_runtime_put() to return an int, but that
return value is never used. It also passes the return value of
pm_runtime_put() to the caller which is not very useful.

Returning an error code from pm_runtime_put() merely means that it has
not queued up a work item to check whether or not the device can be
suspended and there are many perfectly valid situations in which that
can happen, like after writing "on" to the devices' runtime PM "control"
attribute in sysfs for one example.

Modify phy_pm_runtime_put() to discard the pm_runtime_put() return
value and change its return type to void. Also drop the redundant
pm_runtime_enabled() call from there.

No intentional functional impact.

This will facilitate a planned change of the pm_runtime_put() return
type to void in the future.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/2556645.jE0xQCEvom@rafael.j.wysocki
Signed-off-by: Vinod Koul <vkoul@kernel.org>