pinctrl: imx: Add the zero base flag for imx93

On i.MX93, the pin mux reg offset is from 0x0,
so need to add the 'ZERO_OFFSET_VALID' flag to make
sure the pin at mux offset 0 can be found.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Link: https://lore.kernel.org/r/20220613031854.1571357-1-ping.bai@nxp.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>