[U-Boot] fsl_esdhc: Touch only relevant sys ctrl bits

[Andy Fleming]

On Mon, Jul 15, 2013 at 03:44:29PM +0200, Dirk Behme wrote:
> Dealing with the sys ctrl register should touch only the
> relevant bits and not accidently the whole register. On i.MX6,
> the sys control register contains bits which shouldn't be reset to
> 0, e.g. SYS_CTRL[3-0] and IPP_RST_N (SYS_CTRL[23]).
> 
> Do this by read/modify/write instead of just a 32bit write.
> 
> Signed-off-by: Dirk Behme <dirk.behme at de.bosch.com>
> Acked-by: Stefano Babic <sbabic at denx.de>

Applied, thanks!

Andy