drm/amd/display: Call FP Protect Before Mode Programming/Mode Support

[Why]
Memory allocation occurs within dml21_validate() for adding phantom planes.
May cause kernel to be tainted due to usage of FP Start.

[How]
Move FP start from dml21_validate to before mode programming/mode support.
Calculations requiring floating point are all done within mode programming
or mode support.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Austin Zheng <Austin.Zheng@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Austin Zheng

drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c

@@ -234,7 +234,9 @@ static bool dml21_mode_check_and_programming(const struct dc *in_dc, struct dc_s
 	if (!result)
 		return false;
 
+	DC_FP_START();
 	result = dml2_build_mode_programming(mode_programming);
+	DC_FP_END();
 	if (!result)
 		return false;
 
@@ -277,7 +279,9 @@ static bool dml21_check_mode_support(const struct dc *in_dc, struct dc_state *co
 	mode_support->dml2_instance = dml_init->dml2_instance;
 	dml21_map_dc_state_into_dml_display_cfg(in_dc, context, dml_ctx);
 	dml_ctx->v21.mode_programming.dml2_instance->scratch.build_mode_programming_locals.mode_programming_params.programming = dml_ctx->v21.mode_programming.programming;
+	DC_FP_START();
 	is_supported = dml2_check_mode_supported(mode_support);
+	DC_FP_END();
 	if (!is_supported)
 		return false;
 
@@ -288,16 +292,12 @@ bool dml21_validate(const struct dc *in_dc, struct dc_state *context, struct dml
 {
 	bool out = false;
 
-	DC_FP_START();
-
 	/* Use dml_validate_only for fast_validate path */
 	if (fast_validate)
 		out = dml21_check_mode_support(in_dc, context, dml_ctx);
 	else
 		out = dml21_mode_check_and_programming(in_dc, context, dml_ctx);
 
-	DC_FP_END();
-
 	return out;
 }