ARM: OMAP2+: omap2plus_defconfig: enable OMAP DMA engine support

commit 13f30fc893e4610f67dd7a8b0b67aec02eac1775
Author: Russell King <rmk+kernel@arm.linux.org.uk>
Date:   Sat Apr 21 22:41:10 2012 +0100

    mmc: omap: remove private DMA API implementation

removed the private DMA API implementation from the OMAP mmc host to
make it use exclusively the DMA engine API.

Unfortunately the omap2plus_defconfig doesn't enable this feature
leading to the following error on an IGEPv2 Rev.C (and probably on most
boards with MMC support):

[    2.199981] omap_hsmmc omap_hsmmc.1: unable to obtain RX DMA engine channel 48
[    2.215087] omap_hsmmc omap_hsmmc.0: unable to obtain RX DMA engine channel 62

Signed-off-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>