drm/amd/display: Fix type mismatches using guards and explicit casts

drm/amd/display: Fix type mismatches using guards and explicit casts

[Why]
Address signed/unsigned comparison warnings across dc paths to keep
builds warning-clean and improve type safety at comparison boundaries.
Most warnings came from signed loop/index temporaries compared against
unsigned counters and table sizes, plus a smaller number of mixed
signed/unsigned clock, bandwidth, and geometry comparisons.

[How]
Aligned iterator and temporary variable types with the semantic type
of the compared bounds. Used unsigned indices for loops bounded by unsigned
counters and table sizes, while retaining signed types where values are
semantically signed or participate in arithmetic that may legitimately go
negative. Where mixed signed/unsigned comparisons are intentional, applied
explicit boundary casts or guarded comparisons instead of broad type
changes.

No functional behavior changes are intended; this is a warning-resolution
and type-alignment cleanup.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Gaghik Khachatrian <gaghik.khachatrian@amd.com>
Signed-off-by: James Lin <pinglei.lin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>