drm/amd/display: Revert "drm/amd/display: Fix AMDGPU_MAX_BL_LEVEL value"

This reverts commit 66abb99.
This broke custom brightness curves but it wasn't obvious because
of other related changes. Custom brightness curves are always
from a 0-255 input signal. The correct fix was to fix the default
value which was done by [1].

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4412
Link: https://lore.kernel.org/amd-gfx/0f094c4b-d2a3-42cd-824c-dc2858a5618d@kernel.org/T/#m69f875a7e69aa22df3370b3e3a9e69f4a61fdaf2
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 6ec8a5c)
Cc: stable@vger.kernel.org

Author: superm1

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -4756,16 +4756,16 @@ static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps,
 	return 1;
 }
 
-/* Rescale from [min..max] to [0..MAX_BACKLIGHT_LEVEL] */
+/* Rescale from [min..max] to [0..AMDGPU_MAX_BL_LEVEL] */
 static inline u32 scale_input_to_fw(int min, int max, u64 input)
 {
-	return DIV_ROUND_CLOSEST_ULL(input * MAX_BACKLIGHT_LEVEL, max - min);
+	return DIV_ROUND_CLOSEST_ULL(input * AMDGPU_MAX_BL_LEVEL, max - min);
 }
 
-/* Rescale from [0..MAX_BACKLIGHT_LEVEL] to [min..max] */
+/* Rescale from [0..AMDGPU_MAX_BL_LEVEL] to [min..max] */
 static inline u32 scale_fw_to_input(int min, int max, u64 input)
 {
-	return min + DIV_ROUND_CLOSEST_ULL(input * (max - min), MAX_BACKLIGHT_LEVEL);
+	return min + DIV_ROUND_CLOSEST_ULL(input * (max - min), AMDGPU_MAX_BL_LEVEL);
 }
 
 static void convert_custom_brightness(const struct amdgpu_dm_backlight_caps *caps,