OMAPDSS: DISPC: Remove hardcoded use of PPL in five tap clock calculation

The function calc_fclk_five_taps() uses a fixed value of pixels per line which
is used in calculations to get the minimum fclk needed for scaling with five
taps to work.

Remove this by providing the width of the panel connected to the manager.

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