drm/i915: compute pipe bpp from link bandwidth management

drm/i915: compute pipe bpp from link bandwidth management

Since intel_fdi_compute_pipe_bpp() is no longer FDI-specific and
now applies to all connectors. Move it to intel_link_bw.c,
and rename to intel_link_bw_compute_pipe_bpp().

v2: Remove unused header file.

Cc: Shankar Uma <uma.shankar@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Vidya Srinivas <vidya.srinivas@intel.com>
Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
[Imre: Remove unused intel_fdi.h include from intel_hdmi.c]
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250901055721.219995-3-shawn.c.lee@intel.com