ARM: dts: berlin: add the SDHCI nodes for the BG2Q

Add the SDHCI nodes for the Marvell Berlin BG2Q, using the mrvl,pxav3-mmc
driver.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>