OMAP: DSS2: DSI: configure all DSI VCs

Instead of configuring only VC0 to be usable, configure all four VCs
similarly. This is needed to utilize the other VCs.

Setting the FIFO sizes evenly for all VCs, regardless of how many VCs are
actually used, is not optimal. However, this affects only cases when
larger amounts of data are written or read via L4, meaning that normal use
cases are not affected.

At some point this could be optimized better to suit different use cases.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>