spi/dw_spi: move dw_spi.h into drivers/spi

include/linux/dw_spi.h only includes driver internal data.  It doesn't
expose a platform_data configuration structure or similar (at least
nothing in-tree).  This patch moves the header into drivers/spi so
that the scope is limited to only the dw_spi_*.c driver files

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Feng Tang <feng.tang@intel.com>
Cc: spi-devel-general@lists.sourceforge.net
diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 22af77f..9a61964 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -22,10 +22,10 @@
 #include <linux/highmem.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
-
-#include <linux/spi/dw_spi.h>
 #include <linux/spi/spi.h>
 
+#include "dw_spi.h"
+
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #endif