staging: line6/midibuf.c changed printk(KERN_DEBUG, ... to pr_debug(

Changed printk(KERN_DEBUG, ...) call to pr_debug call in function
void line6_midibuf_status(struct MidiBuffer *this)

Signed-off-by: Johannes Thumshirn <morbidrsa@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>