[U-Boot] "Writing to MMC(%d)... failed"

[Nathan]

I think I've been able to narrow down, a bit, where the issue is coming from.

"mmc_set_blocklen" led me to "mmc_send_cmd" which showed that there is
the "CONFIG_MMC_TRACE" I could use.

A notable difference between hardkernel's u-boot and mainline was the
"uint flags;" was no longer in the "mmc_cmd" struct.

I did see that this removal was noted as being a problem back in 2012:
http://lists.denx.de/pipermail/u-boot/2012-September/133409.html

The result from "saveenv":

Odroid # saveenv


Saving Environment to MMC...


Writing to MMC(0)... CMD_SEND:16


                ARG                      0x00000200


ret: -19


                MMC_RSP_R1,5,6,7         0x00000000

I added the "printf" for "ret".