amdgpu/dc/calcs: Consolidate redundant CFLAGS

Use a variable for common CFLAGS instead of specifying the same flags
for every source file.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -24,9 +24,11 @@
 # It calculates Bandwidth and Watermarks values for HW programming
 #
 
-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 -Wno-tautological-compare
+calcs_ccflags := -mhard-float -msse -mpreferred-stack-boundary=4
+
+CFLAGS_dcn_calcs.o := $(calcs_ccflags)
+CFLAGS_dcn_calc_auto.o := $(calcs_ccflags)
+CFLAGS_dcn_calc_math.o := $(calcs_ccflags) -Wno-tautological-compare
 
 BW_CALCS = dce_calcs.o bw_fixed.o custom_float.o