musb: add high bandwidth ISO support

Tested on OMAP3 host side with Creative (Live! Cam Optia) USB camera
which uses high bandwidth isochronous IN endpoints.  FIFO mode 4 is
updated to provide the needed 4K endpoint buffer without breaking
the g_nokia composite gadget configuration.  (This is the only
gadget driver known to use enough endpoints to notice the change.)

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>