drm/amd/display: Use macro for isnan check

In code provided by HW teams we do a NaN check on floats
by comparing the number against itself. This confuses most
people including myself. Macro it out to make it self-explanatory.

Don't do a NaN check for int.

v2: parantheses around 'number' expression

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

drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c

@@ -25,37 +25,35 @@
 
 #include "dcn_calc_math.h"
 
+#define isNaN(number) ((number) != (number))
+
 float dcn_bw_mod(const float arg1, const float arg2)
 {
-	if (arg1 != arg1)
+	if (isNaN(arg1))
 		return arg2;
-	if (arg2 != arg2)
+	if (isNaN(arg2))
 		return arg1;
 	return arg1 - arg1 * ((int) (arg1 / arg2));
 }
 
 float dcn_bw_min2(const float arg1, const float arg2)
 {
-	if (arg1 != arg1)
+	if (isNaN(arg1))
 		return arg2;
-	if (arg2 != arg2)
+	if (isNaN(arg2))
 		return arg1;
 	return arg1 < arg2 ? arg1 : arg2;
 }
 
 unsigned int dcn_bw_max(const unsigned int arg1, const unsigned int arg2)
 {
-	if (arg1 != arg1)
-		return arg2;
-	if (arg2 != arg2)
-		return arg1;
 	return arg1 > arg2 ? arg1 : arg2;
 }
 float dcn_bw_max2(const float arg1, const float arg2)
 {
-	if (arg1 != arg1)
+	if (isNaN(arg1))
 		return arg2;
-	if (arg2 != arg2)
+	if (isNaN(arg2))
 		return arg1;
 	return arg1 > arg2 ? arg1 : arg2;
 }