staging: line6: Remove line6_pod_transmit_paramter()

This function was no longer used as of commit 28079044 (staging:
line6: drop MIDI parameter sysfs attrs).

Signed-off-by: Chris Rorvick <chris@rorvick.com>
Reviewed-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>