omap: mux: Mux 2430 USB0HS_STP in board-2430.c

Use new mux functions for that. There are no other known 2430 boards
that need this mux.

Cc: Felipe Balbi <felipe.balbi@nokia.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>