mvebu: pinctrl: sync compatible string with Linux 4.17-rc4

For pinctrl driver of mvebu, the compatible strings
supported are defined differently from Linux version.
The patch aligned the compatible string with
Linux 4.17-rc4.

Signed-off-by: Evan Wang <xswang@marvell.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>