drm/amd: Copy entire structure in amdgpu_acpi_get_backlight_caps()

As new members are introduced to the structure copying the entire
structure will help avoid missing them.

Reviewed-by: Alex Hung <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mario Limonciello <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 {
 	struct amdgpu_atif *atif = &amdgpu_acpi_priv.atif;
 
-	caps->caps_valid = atif->backlight_caps.caps_valid;
-	caps->min_input_signal = atif->backlight_caps.min_input_signal;
-	caps->max_input_signal = atif->backlight_caps.max_input_signal;
-	caps->ac_level = atif->backlight_caps.ac_level;
-	caps->dc_level = atif->backlight_caps.dc_level;
+	memcpy(caps, &atif->backlight_caps, sizeof(*caps));
 }
 
 /**