drm/amd/display: Ignore wrong tautological warning

Some of our HW calcs functions compares a var against
itself to check for NaN. Gcc isn't fond of it and wrongfully
warns about a tautological comparison. Disable this check
for dcn_calcs_math.c.

Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/calcs/Makefile

@@ -5,7 +5,7 @@
 
 CFLAGS_dcn_calcs.o := -mhard-float -msse -mpreferred-stack-boundary=4
 CFLAGS_dcn_calc_auto.o := -mhard-float -msse -mpreferred-stack-boundary=4
-CFLAGS_dcn_calc_math.o := -mhard-float -msse -mpreferred-stack-boundary=4
+CFLAGS_dcn_calc_math.o := -mhard-float -msse -mpreferred-stack-boundary=4 -Wno-tautological-compare
 
 BW_CALCS = dce_calcs.o bw_fixed.o custom_float.o