drm/amd/display: Use true/false for boolean variables in DML2 core files

Replace 0 and 1 with false and true for boolean variables in
dml2_core_dcn4_calcs.c and dml2_core_utils.c to align with the Linux
kernel coding style guidelines, which recommend using C99 bool type
with true/false values.

Signed-off-by: Ivan Shamliev <ivan.shamliev.dev@abv.bg>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>