regulator: stm32-vrefbuf: Remove redundant pm_runtime_mark_last_busy() calls

regulator: stm32-vrefbuf: Remove redundant pm_runtime_mark_last_busy() calls

pm_runtime_put_autosuspend(), pm_runtime_put_sync_autosuspend(),
pm_runtime_autosuspend() and pm_request_autosuspend() now include a call
to pm_runtime_mark_last_busy(). Remove the now-reduntant explicit call to
pm_runtime_mark_last_busy().

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Link: https://patch.msgid.link/20250704075444.3221445-1-sakari.ailus@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>