drm/amdgpu: Fix invalid number of character '{' in amdgpu_acpi_init

Fix follow warning:
Checking drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c...
[drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:770]: (error) Invalid number
of character '{' when these macros are defined: ''.
Checking drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c: CONFIG_ACPI...
[drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:770]: (error) Invalid number
of character '{' when these macros are defined: 'CONFIG_ACPI'.
......
Checking drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c: CONFIG_X86...
[drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:770]: (error) Invalid number
of character '{' when these macros are defined: 'CONFIG_X86'.
Checking drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c: _X86_...
[drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:770]: (error) Invalid number
of character '{' when these macros are defined: '_X86_'.
Checking drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c: __linux__...
[drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:770]: (error) Invalid number
of character '{' when these macros are defined: '__linux__'.

Fixes: 97d798b2 ("drm/amdgpu: simplify ATIF backlight handling")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c

@@ -806,8 +806,8 @@ int amdgpu_acpi_init(struct amdgpu_device *adev)
 	}
 	adev->atif = atif;
 
-	if (atif->notifications.brightness_change) {
 #if defined(CONFIG_BACKLIGHT_CLASS_DEVICE) || defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)
+	if (atif->notifications.brightness_change) {
 		if (amdgpu_device_has_dc_support(adev)) {
 #if defined(CONFIG_DRM_AMD_DC)
 			struct amdgpu_display_manager *dm = &adev->dm;