launcher: Drop unecessary checks for drm_fd == -1

We never get into this case, and if we do, we just want to pass the invalid
fd through to the underlying ioctl and get the error that way."

src/launcher-util.c

@@ -69,25 +69,20 @@ struct weston_launcher {
 static int
 drm_drop_master(int drm_fd)
 {
-	if (drm_fd != -1)
 	return drmDropMaster(drm_fd);
-	return -EBADF;
 }
 static int
 drm_set_master(int drm_fd)
 {
-	if (drm_fd != -1)
 	return drmSetMaster(drm_fd);
-	return -EBADF;
 }
 static int
 drm_is_master(int drm_fd)
 {
 	drm_magic_t magic;
-	if (drm_fd != -1)
+
 	return drmGetMagic(drm_fd, &magic) == 0 &&
 		drmAuthMagic(drm_fd, magic) == 0;
-	return 0;
 }
 #else
 static int drm_drop_master(int drm_fd) {return 0;}