pinctrl: imx: off by one in imx_pinconf_group_dbg_show()

The > should really be >= here.  It's harmless because
pinctrl_generic_get_group() will return a NULL if group is invalid.

Fixes: ae75ff81

 ("pinctrl: pinctrl-imx: add imx pinctrl core driver")
Reported-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>