drm/radeon: make array encoded_lanes static

Don't populate the read-only array encoded_lanes on the stack but instead it
static. Also makes the object code smaller by 97 bytes:

Before:
   text    data    bss     dec    hex filename
  38899    8064      0   46963   b773 ./drivers/gpu/drm/radeon/r600_dpm.o

After:
   text    data    bss     dec    hex filename
  38738    8128      0   46866   b712 ./drivers/gpu/drm/radeon/r600_dpm.o

(gcc version 11.2.0)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/r600_dpm.c

@@ -1361,7 +1361,9 @@ u16 r600_get_pcie_lane_support(struct radeon_device *rdev,
 
 u8 r600_encode_pci_lane_width(u32 lanes)
 {
-	u8 encoded_lanes[] = { 0, 1, 2, 0, 3, 0, 0, 0, 4, 0, 0, 0, 5, 0, 0, 0, 6 };
+	static const u8 encoded_lanes[] = {
+		0, 1, 2, 0, 3, 0, 0, 0, 4, 0, 0, 0, 5, 0, 0, 0, 6
+	};
 
 	if (lanes > 16)
 		return 0;