spi: Move freescale-specific code into a private header

At present there are two SPI functions only used by freescale which are
defined in the spi_flash.h header. One function name matches an existing
generic SPL function.

Move these into a private header to avoid confusion.

Arcturus looks like it does not actually support SPI, so drop the SPI code
from that board.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/board/freescale/p1010rdb/spl.c b/board/freescale/p1010rdb/spl.c
index f858408..9844194 100644
--- a/board/freescale/p1010rdb/spl.c
+++ b/board/freescale/p1010rdb/spl.c
@@ -12,6 +12,7 @@
 #include <i2c.h>
 #include <fsl_esdhc.h>
 #include <spi_flash.h>
+#include "../common/spl.h"
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -103,7 +104,7 @@
 #ifdef CONFIG_SPL_MMC_BOOT
 	mmc_boot();
 #elif defined(CONFIG_SPL_SPI_BOOT)
-	spi_boot();
+	fsl_spi_boot();
 #elif defined(CONFIG_SPL_NAND_BOOT)
 	nand_boot();
 #endif