HID: picoLCD: optimize for inactive debugfs

HID: picoLCD: optimize for inactive debugfs

Matthieu CASTET adjusted picolcd_debug_out_report() to only operate when
there is an active listener on debugfs for events.

Do the same on the more important picolcd_debug_raw_event() that is
called in interrupt context as opposed to picolcd_debug_out_report()
which happens in whichever context that sends reports to device.

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>