OMAPDSS: DSI: turn hsdivs fields to arrays

We are creating a common DSS PLL code, so having fixed DSI specific
hsdiv fields in the clock information is not ok.

This patch changes the hsdiv fields to arrays, so that we can use all
the 4 possible hsdiv outputs (DSI only usees 2), and we have generic way
to access the hsdivs.

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