usb: musb: remove board_data parameter from musb_platform_init()

Removed the board_data parameter being
passed to musb_platform_init function
as board_data can be extracted from
device structure which is already member
of musb structure.

Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Hema HK <hemahk@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>