HID: hid-picolcd: Fix memory leak in picolcd_debug_out_report()

We have a memory leak in drivers/hid/hid-picolcd.c::picolcd_debug_out_report()
in an error path..  We are not always freeing the memory allocated to
'buff' - this patch makes sure we always kfree() what we allocate with
kmalloc() when it is no longer needed.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>