arm64: a37xx: dts: Add additional pinctrl definition

arm64: a37xx: dts: Add additional pinctrl definition

Add mmc pins, pcie pins and sdio pins definition and do these pins'
configuration for DB board and espressobin board;
Add uart2 pins configuration for DB board.

Reviewed-on: http://vgitil04.il.marvell.com:8080/40914
Reviewed-by: Wilson Ding <[email protected]>
Tested-by: Wilson Ding <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: Stefan Roese <[email protected]>
Signed-off-by: Ken Ma <[email protected]>
Signed-off-by: Stefan Roese <[email protected]>