The channel_names list didn't have a string populated for LCD3 manager, this
results in a crash when the display's output is connected to LCD3. Add an entry
for LCD3.
Reported-by: NSomnath Mukherjee <somnath@ti.com>
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>