As per Bsepc:49259, Bigjoiner BW check puts restriction on the
compressed bpp for a given CDCLK, pixelclock in cases where
Bigjoiner + DSC are used.

Currently compressed bpp is computed first, and it is ensured that
the bpp will work at least with the max CDCLK freq.

Since the CDCLK is computed later, lets account for Bigjoiner BW
check while calculating Min CDCLK.

v2: Use pixel clock in the bw calculations. (Ville)

v3: Use helper to account for FEC overhead. (Stan)
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230817142459.89764-7-ankit.k.nautiyal@intel.com