Revert SeaBIOS change due to overzealous commit -a

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/roms/seabios b/roms/seabios
index 06d0bdd9e2e20377b3180e4986b14c8549b393e4..cc975646af69f279396d4d5e1379ac6af80ee637 160000 (submodule)
--- a/roms/seabios
+++ b/roms/seabios
@@ -1 +1 @@
-Subproject commit 06d0bdd9e2e20377b3180e4986b14c8549b393e4
+Subproject commit cc975646af69f279396d4d5e1379ac6af80ee637