ARM: OMAP: Fix musb_core parameter passing to cppi start

cppi_controller_start() expects a struct dma_controller as parameter
and not dma_controller private_data. Current implementation crashes
with e.g.

Internal error: Oops: 805 [#1]
Modules linked in:
CPU: 0    Not tainted  (2.6.23-rc4-davinci1 #2)
PC is at cppi_controller_start+0x18/0x140
LR is at musb_probe+0x1f4/0x824

Fix this. Initial proposal for fix by David Brownell. Thanks!

Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>