[U-Boot] mmc write bug fix

[Andy Fleming]

On Wed, May 22, 2013 at 01:19:43PM +0200, Ruud Commandeur wrote:
> This patch fixes a bug related to mmc writes.
> 
> When doing fatwrites on an SD-Card, MMC bus problems can occur. Depending
> on the size of the file, "MMC0: Bus busy timeout!" is reported, resulting
> in an SD-Card that is no longer responding.
> It appears to be, that set_cluster can be called with a size being zero.
> That can be with a file that has a size being an exact multiple
> (including 0) of the clustersize, but also for files that are smaller than
> the size of one cluster.
> The same problem occurs if the "mmc write" command is given with a block
> count being 0.
> 
> By adding a check for the block count being zero in mmc_write_blocks
> (drivers/mmc.c), this problem is solved.
> 
> Signed-off-by: Ruud Commandeur <rcommandeur at clb.nl>
> Cc: Tom Rini <trini at ti.com>
> Cc: Benoît Thébaudeau <benoit.thebaudeau at advansee.com>
> Cc: Mats Karrman <Mats.Karrman at tritech.se>
> Cc: Andy Fleming <afleming at gmail.com>


Please use git to generate patches, if possible. This didn't apply
cleanly, and required that I apply it by hand.

However, applied it is.

Andy