ARM: at91/dt: add pullup on mmc2 data signals

MMC data lines may be left floating if nothing is currently driving the
data lines, which is the case when mmc is in idle state, thus consuming
a useless extra amount of power. Add pullup on mmc2 data signals in the
same way it was previously done for mmc0 and mmc1.

Signed-off-by: Sylvain Rochet <sylvain.rochet@finsecur.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>