Remove pm_runtime_mark_last_busy() call that wasn't need in the probe
since the device should be put to sleep.

Clarification from Matt:
Basically it going to be suspended once pm_runtime_idle() is called,
and setting the last busy is useless and not needed.
Clearly this doesn't affect the device running but just makes the code
more consistent with other uses.
Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>