davinci, mmc: Added a delay reading ext CSD register

Without this additional delay, some eMMC don't negotiate properly bus width
Tested on:
 - Toshiba THGBM2G8D8FBAIB
 - Toshiba THGBM4G4D1HBAR
 - Micron MTFC4GMVEA (the one giving the problem)
 - Hynix H26M64002BNR
 - SanDisk SDIN5E1-32G

Signed-off-by: Davide Bonfanti <davide.bonfanti@bticino.it>
Acked-by: Tom Rini <trini@ti.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>

drivers/mmc/davinci_mmc.c

@@ -285,8 +285,11 @@ dmmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 			 */
 			if (bytes_left > fifo_bytes)
 				dmmc_wait_fifo_status(regs, 0x4a);
-			else if (bytes_left == fifo_bytes)
+			else if (bytes_left == fifo_bytes) {
 				dmmc_wait_fifo_status(regs, 0x40);
+				if (cmd->cmdidx == MMC_CMD_SEND_EXT_CSD)
+					udelay(600);
+			}
 
 			for (i = 0; bytes_left && (i < fifo_words); i++) {
 				cmddata = get_val(&regs->mmcdrr);