ARM: davinci: board-da850-evm: fix GPIO lookup for MMC/SD

The GPIO chip is called davinci_gpio.0 in legacy mode. Fix it, so that
mmc can correctly lookup the wp and cp gpios. Also fix the GPIO numbers
as they are not offsets within a bank.

Note that it is the gpio-davinci driver that sets the gpiochip label to
davinci_gpio.0.

Fixes: bdf0e836 ("ARM: davinci: da850-evm: use gpio descriptor for mmc pins")
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>