drm/i915: Add PLANE_CUS_CTL restriction in max_width

PLANE_CUS_CTL has a restriction of 4096 width even though
PLANE_SIZE and scaler size registers supports max 5120.
Take care of this restriction in max_width.

Without this patch, when 5k content is sent on HDR plane
with NV12 content, FIFO underrun is seen and screen blanks
out.

v2: Addressed review comments from Ville. Added separate
functions for max_width - for HDR and SDR

v3: Addressed review comments from Ville. Changed names of
HDR and SDR max_width functions to icl_hdr_plane_max_width
and icl_sdr_plane_max_width

v4: Fixed paranthesis alignment. No code change

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
[vsyrjala: Fix alignment]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211202110836.17536-1-vidya.srinivas@intel.com