drm/amd/display: Fix narrowing boundaries and eDP parser assignment

drm/amd/display: Fix narrowing boundaries and eDP parser assignment

[Why] drm/amd/display had implicit integer narrowing at protocol/storage boundaries
and an incomplete eDP assignment in integrated info parsing.

[How] Apply explicit boundary casts for intentional narrowing, keep intermediate math
in wider types, and restore explicit eDP field mapping in v2.2 parser.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Gaghik Khachatrian <gaghik.khachatrian@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>