media: rcar-csi2: Simplify rcsi2_calc_mbps()

media: rcar-csi2: Simplify rcsi2_calc_mbps()

Instead of taking the bpp and the number of lanes as parameters to
rcsi2_calc_mbps(), change the function to get those parameters inside
the function. This centralizes the code a bit and makes it easier to add
streams support.

Also, in the future when the legacy (non-link-freq) code is removed,
there will be no need to change rcsi2_calc_mbps() parameters.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>