pinctrl: imx: detect uninitialized pins

The pinctrl driver initialized the register offsets for the pins
with 0. On Vybrid an offset of 0 is a valid offset for the pinctrl
mux register. So far, this was solved using the ZERO_OFFSET_VALID
flag which allowed offsets of 0. However, this does not allow to
verify whether a pins struct imx_pmx_func was initialized or not.

Use signed offset values for register offsets and initialize those
with -1 in order to detect uninitialized offset values reliable.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/freescale/pinctrl-vf610.c b/drivers/pinctrl/freescale/pinctrl-vf610.c
index bddd913..b788e15 100644
--- a/drivers/pinctrl/freescale/pinctrl-vf610.c
+++ b/drivers/pinctrl/freescale/pinctrl-vf610.c
@@ -299,7 +299,7 @@
 static struct imx_pinctrl_soc_info vf610_pinctrl_info = {
 	.pins = vf610_pinctrl_pads,
 	.npins = ARRAY_SIZE(vf610_pinctrl_pads),
-	.flags = ZERO_OFFSET_VALID | SHARE_MUX_CONF_REG,
+	.flags = SHARE_MUX_CONF_REG,
 };
 
 static struct of_device_id vf610_pinctrl_of_match[] = {