ARM: davinci: da850: override mmc DT node device name

Populate OF_DEV_AUXDATA with desired device name expected by
davinci_mmc driver. Without this clk_get of davinci_mmc DT driver
fails.

Signed-off-by: Manjunathappa, Prakash <prakash.pm@ti.com>
Cc: linux-mmc@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: davinci-linux-open-source@linux.davincidsp.com
Cc: devicetree-discuss@lists.ozlabs.org
Cc: cjb@laptop.org
Cc: Sekhar Nori <nsekhar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>