spl: mmc: use block device number, not hard-coded 0

In order to support boot from multiple devices through board_boot_order,
it's necessary to use the block number of a device.

The use of a hard-coded 0 for the device number also creates a need
to re-order block devices for use in SPL like this:
	http://git.denx.de/?p=u-boot.git;a=blob;f=board/freescale/mx6slevk/mx6slevk.c;hb=HEAD#l195



Signed-off-by: Eric Nelson <eric@nelint.com>

common/spl/spl_mmc.c

@@ -23,12 +23,13 @@ static int mmc_load_image_raw_sector(struct mmc *mmc, unsigned long sector)
 	unsigned long count;
 	u32 image_size_sectors;
 	struct image_header *header;
+	int dev_num = mmc->block_dev.dev;
 
 	header = (struct image_header *)(CONFIG_SYS_TEXT_BASE -
 					 sizeof(struct image_header));
 
 	/* read image header to find the image size & load address */
-	count = mmc->block_dev.block_read(0, sector, 1, header);
+	count = mmc->block_dev.block_read(dev_num, sector, 1, header);
 	debug("read sector %lx, count=%lu\n", sector, count);
 	if (count == 0)
 		goto end;
@@ -45,7 +46,7 @@ static int mmc_load_image_raw_sector(struct mmc *mmc, unsigned long sector)
 			     mmc->read_bl_len;
 
 	/* Read the header too to avoid extra memcpy */
-	count = mmc->block_dev.block_read(0, sector, image_size_sectors,
+	count = mmc->block_dev.block_read(dev_num, sector, image_size_sectors,
 					  (void *)(ulong)spl_image.load_addr);
 	debug("read %x sectors to %x\n", image_size_sectors,
 	      spl_image.load_addr);
@@ -149,7 +150,8 @@ static int mmc_load_image_raw_os(struct mmc *mmc)
 {
 	unsigned long count;
 
-	count = mmc->block_dev.block_read(0,
+	count = mmc->block_dev.block_read(
+		mmc->block_dev.dev,
 		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
 		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS,
 		(void *) CONFIG_SYS_SPL_ARGS_ADDR);