dm: Add spi.h header to a few files

Some files are using SPI functions but not explitly including the SPI
header file. Fix this, since driver model needs it.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>

common/env_sf.c

@@ -12,6 +12,7 @@
 #include <common.h>
 #include <environment.h>
 #include <malloc.h>
+#include <spi.h>
 #include <spi_flash.h>
 #include <search.h>
 #include <errno.h>

drivers/dfu/dfu_sf.c

@@ -9,6 +9,7 @@
 #include <errno.h>
 #include <div64.h>
 #include <dfu.h>
+#include <spi.h>
 #include <spi_flash.h>
 
 static long dfu_get_medium_size_sf(struct dfu_entity *dfu)

drivers/mtd/spi/sf_params.c

@@ -7,6 +7,7 @@
  */
 
 #include <common.h>
+#include <spi.h>
 #include <spi_flash.h>
 
 #include "sf_internal.h"