Support for QAM modulation on ATSC

Default is not QAM_AUTO because ATSC is mainly using VSB_8 for non-cable operations.
Patch by Charles Hordis

THANKS

@@ -54,6 +54,7 @@ Carlo Calabrò <murray at via.ecp.fr> - Italian localization
 Carsten Gottbehüt <gottbehuet at active-elements dot de> - v4l hotplug fix
 Carsten Haitzler <raster __at__ rasterman dot com> - x11 fullscreen fix
 Cédric Cocquebert - Misc opengl effects for the OpenGL Video Output. "Panoramix" video filter for image walls with automatic attenuation. Fix on sharpen filter.
+Charles Hordis - QAM modulation on ATSC
 Chris Clepper - OpenGL fix
 Christian Henz - libupnp service discovery plugin, CyberLink UPnP fixes
 Cristian Secară <cristi at secarica dot ro> - Romanian l10n

modules/access/dvb/linux_dvb.c

@@ -794,8 +794,13 @@ static fe_modulation_t DecodeModulationATSC( access_t *p_access )
 {
     switch( var_GetInteger( p_access, "dvb-modulation" ) )
     {
+        case 0:     return QAM_AUTO;
         case 8:     return VSB_8;
         case 16:    return VSB_16;
+        case 32:    return QAM_32;
+        case 64:    return QAM_64;
+        case 128:   return QAM_128;
+        case 256:   return QAM_256;
         default:
             msg_Dbg( p_access, "ATSC modulation not set, using VSB 8");
             return VSB_8;