Tweak get_available_video_modes() interface.

[nageru] / bmusb

diff --git a/bmusb b/bmusb
index 753cbaf5cec7411bdfe5171404c8586b8015faec..487a136592e4bd5acda92d35cf52fe4489c69bbf 160000 (submodule)
--- a/bmusb
+++ b/bmusb
@@ -1 +1 @@
-Subproject commit 753cbaf5cec7411bdfe5171404c8586b8015faec
+Subproject commit 487a136592e4bd5acda92d35cf52fe4489c69bbf