mb/hp/z220_sff_workstation: Add empty lines after "SPDX"

Change-Id: Ief8df9ef0d6ecb675680aa5120738f5099034139
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45245
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/hp/z220_sff_workstation/mainboard.c

@@ -1,4 +1,5 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <device/device.h>
 #include <drivers/intel/gma/int15.h>
 #include <southbridge/intel/bd82x6x/pch.h>