usb: musb: remove adjust_channel_params() callback from musb_platform_ops

Now Blackfin support is removed, nobody uses adjust_channel_params() any
more, so remove it from struct musb_platform_ops.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>