scsi: ufs: core: Discard pm_runtime_put() return values

The ufshcd driver defines ufshcd_rpm_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 ufshcd_rpm_put() to discard the pm_runtime_put() return value
and change its return type to void.

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>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://patch.msgid.link/2781685.BddDVKsqQX@rafael.j.wysocki