qdexternal: Only write HPDOption when HDMI is connected

* Prevents E/qdexternal( 1081): writeHPDOption: state file '/sys/devices/virtual/graphics/fb-1/hpd' not found : ret-1 err str: No such file or directory

Change-Id: If896d73e7a449ad717fd0cb2c269be5d2545d4e7
Signed-off-by: Brandon McAnsh <brandon.mcansh@gmail.com>