tidy: Clean up code stripping dvd or bluray device names.

The clang-tidy bugprone "branch clone" checker pointed out two places
where it appears that the bodies of an if/then/else clause were
duplicated.  It appears that this code was designed to strip a device
name from the front of the string, and replace a double "//" with a
single slash.  Rewrite these two clauses to simplify them.

https://clang.llvm.org/extra/clang-tidy/checks/bugprone-branch-clone.html

mythtv/libs/libmythtv/Bluray/bdringbuffer.cpp

@@ -146,12 +146,12 @@ BDInfo::BDInfo(const QString &filename)
     LOG(VB_PLAYBACK, LOG_INFO, QString("BDInfo: Trying %1").arg(filename));
     QString name = filename;
 
-    if (name.startsWith("bd://"))
-        name.remove(0,4);
-    else if (name.startsWith("bd:/"))
-        name.remove(0,3);
-    else if (name.startsWith("bd:"))
+    if (name.startsWith("bd:"))
+    {
         name.remove(0,3);
+        while (name.startsWith("//"))
+            name.remove(0,1);
+    }
 
     // clean path filename
     name = QDir(QDir::cleanPath(name)).canonicalPath();

mythtv/libs/libmythtv/DVD/dvdringbuffer.cpp

@@ -50,12 +50,12 @@ DVDInfo::DVDInfo(const QString &filename)
 {
     LOG(VB_PLAYBACK, LOG_INFO, QString("DVDInfo: Trying %1").arg(filename));
     QString name = filename;
-    if (name.startsWith("dvd://"))
-        name.remove(0,5);
-    else if (name.startsWith("dvd:/"))
-        name.remove(0,4);
-    else if (name.startsWith("dvd:"))
+    if (name.startsWith("dvd:"))
+    {
         name.remove(0,4);
+        while (name.startsWith("//"))
+            name.remove(0,1);
+    }
 
     QByteArray fname = name.toLocal8Bit();
     dvdnav_status_t res = dvdnav_open(&m_nav, fname.constData());