amdgpu/dc: use kernel ilog2 for log_2.

This should produce the same result.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/basics/conversion.c

@@ -102,13 +102,3 @@ void convert_float_matrix(
 		matrix[i] = (uint16_t)reg_value;
 	}
 }
-
-unsigned int log_2(unsigned int num)
-{
-	unsigned int result = 0;
-
-	while ((num >>= 1) != 0)
-		result++;
-
-	return result;
-}

drivers/gpu/drm/amd/display/dc/basics/conversion.h

@@ -38,6 +38,9 @@ void convert_float_matrix(
 	struct fixed31_32 *flt,
 	uint32_t buffer_size);
 
-unsigned int log_2(unsigned int num);
+static inline unsigned int log_2(unsigned int num)
+{
+	return ilog2(num);
+}
 
 #endif