arm64: a37xx: pinctrl: Fix the pin 23 on south bridge

arm64: a37xx: pinctrl: Fix the pin 23 on south bridge

Pin 23 on South bridge does not belong to the rgmii group. It belongs to
a separate group which can have 3 functions.

Due to this the fix also have to update the way the functions are
managed. Until now each groups used NB_FUNCS(which was 2) functions. For
the mpp23, 3 functions are available but it is the only group which needs
it, so on the loop involving NB_FUNCS an extra test was added to handle
only the functions added.

The bug was visible when the gpio regulator used the gpio 23, the whole
rgmii group was setup to gpio which broke the Ethernet support on the
Armada 3720 DB board. Thanks to this patch, the UHS SD cards (which need
the vqmmc) _and_ the Ethernet work again.

Reviewed-on: http://vgitil04.il.marvell.com:8080/43284
Reviewed-by: Hua Jing <jinghua@marvell.com>
Tested-by: iSoC Platform CI <ykjenk@marvell.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Stefan Roese <sr@denx.de>
Signed-off-by: Ken Ma <make@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>