pinctrl: imx: add imx7ulp driver

i.MX 7ULP has three IOMUXC instances: IOMUXC0 for M4 ports,
IOMUXC1 for A7 ports and IOMUXC DDR for DDR interface.

This patch adds the IOMUXC1 support for A7.
It only supports generic pin config.

Cc: Bai Ping <ping.bai@nxp.com>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>