clients: Improve Samsung BD-J5500 support

From SF user Andrea Odetti:

The Samsung BD J5500 player does not accept some of the DLNA_PN values
used by minidlna for *.mp4 files.

For instance AVC_MP4_MP_HD_720p_AAC and AVC_MP4_BL_L31_HD_AAC are
problematic as the player would simply ignore the files and not show
them.

AVC_MP4_HP_HD_AAC works.

All the files play normally from a USB key.

I've noticed as well that NULL works always, and this is the approach I
have followed.

So I changed minidlna and added a flag to disable DLNA_PN, and this
flag is only used for a Samsung BD J5500 in order not to break other
players, which can handle DLNA_PN properly.

So when a J5500 is connected we simply set DLNA_PN to NULL and
everything works well.

upnpsoap.c

@@ -905,6 +905,9 @@ callback(void *args, int argc, char **argv, char **azColName)
 		else
 			dlna_flags |= DLNA_FLAG_TM_I;
 
+		if( passed_args->flags & FLAG_SKIP_DLNA_PN )
+		        dlna_pn = NULL;
+
 		if( dlna_pn )
 			snprintf(dlna_buf, sizeof(dlna_buf), "DLNA.ORG_PN=%s;"
 			                                     "DLNA.ORG_OP=01;"