spl: Convert boot_device into a struct

At present some spl_xxx_load_image() functions take a parameter and some
don't. Of those that do, most take an integer but one takes a string.

Convert this parameter into a struct so that we can pass all functions the
same thing. This will allow us to use a common function signature.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

arch/arm/mach-sunxi/board.c

@@ -133,7 +133,7 @@ static int gpio_init(void)
 	return 0;
 }
 
-int spl_board_load_image(void)
+int spl_board_load_image(struct spl_boot_device *bootdev)
 {
 	debug("Returning to FEL sp=%x, lr=%x\n", fel_stash.sp, fel_stash.lr);
 	return_to_fel(fel_stash.sp, fel_stash.lr);

arch/arm/mach-uniphier/boot-mode/spl_board.c

@@ -65,7 +65,7 @@ int uniphier_rom_get_mmc_funcptr(int (**send_cmd)(u32, u32),
 	return 0;
 }
 
-int spl_board_load_image(void)
+int spl_board_load_image(struct spl_boot_device *bootdev)
 {
 	int (*send_cmd)(u32 cmd, u32 arg);
 	int (*card_blockaddr)(u32 rca);

arch/sandbox/cpu/spl.c

@@ -38,7 +38,7 @@ void spl_board_announce_boot_device(void)
 	printf("%s\n", fname);
 }
 
-int spl_board_load_image(void)
+int spl_board_load_image(struct spl_boot_device *bootdev)
 {
 	char fname[256];
 	int ret;