test: spl: Add a test for NAND

Add a SPL test for the NAND load method. We use some different functions to
do the writing from the main test since things like nand_write_skip_bad
aren't available in SPL.

We disable BBT scanning, since scan_bbt is only populated when not in SPL.
We use nand_spl_loaders.c as it seems to be common to at least a few boards
already. However, we do not use nand_spl_simple.c because it would require
us to implement cmd_ctrl.  The various nand load functions are adapted from
omap_gpmc. However, they have been modified for simplicity/correctness.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
diff --git a/configs/sandbox_noinst_defconfig b/configs/sandbox_noinst_defconfig
index 09ebafe..0e5f84a 100644
--- a/configs/sandbox_noinst_defconfig
+++ b/configs/sandbox_noinst_defconfig
@@ -51,6 +51,13 @@
 CONFIG_SPL_FS_EXT4=y
 CONFIG_SPL_I2C=y
 CONFIG_SPL_MMC_WRITE=y
+CONFIG_SPL_MTD=y
+CONFIG_SPL_NAND_SUPPORT=y
+CONFIG_SPL_NAND_DRIVERS=y
+CONFIG_SPL_NAND_ECC=y
+CONFIG_SPL_NAND_SOFTECC=y
+CONFIG_SPL_NAND_BASE=y
+CONFIG_SPL_NAND_IDENT=y
 CONFIG_SPL_DM_SPI_FLASH=y
 CONFIG_SPL_NET=y
 CONFIG_SPL_NOR_SUPPORT=y
@@ -183,12 +190,16 @@
 CONFIG_MMC_SANDBOX=y
 CONFIG_MTD=y
 CONFIG_DM_MTD=y
+CONFIG_MTD_CONCAT=y
 CONFIG_MTD_RAW_NAND=y
 CONFIG_SYS_MAX_NAND_DEVICE=8
 CONFIG_SYS_NAND_USE_FLASH_BBT=y
 CONFIG_NAND_SANDBOX=y
+CONFIG_SYS_NAND_BLOCK_SIZE=0x2000
 CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_SYS_NAND_PAGE_SIZE=0x200
+CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
+CONFIG_SYS_NAND_U_BOOT_OFFS=0x0
 CONFIG_SPI_FLASH_SANDBOX=y
 CONFIG_SPI_FLASH_ATMEL=y
 CONFIG_SPI_FLASH_EON=y