Fix several -Wold-style-declaration warnings

Change-Id: Iffe5e652779a13ee7f64696fb5df4a781fe9a632
Signed-off-by: Richard Hughes <richard@hughsie.com>
Reviewed-on: https://review.coreboot.org/c/30404
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/nicintel_spi.c b/nicintel_spi.c
index 4d20c40..f31a2f9 100644
--- a/nicintel_spi.c
+++ b/nicintel_spi.c
@@ -218,7 +218,7 @@
 	return 0;
 }
 
-static int nicintel_spi_i210_enable_flash()
+static int nicintel_spi_i210_enable_flash(void)
 {
 	uint32_t tmp;