pinctrl: pinctrl-mxs: Take care of frees if the kzalloc fails

if there is no purecfg , the group pointer is allocated using kzalloc and if it
fails to allocate, we wont free the new_map,

if config is true, we call kmemdup and if it
fails to do so we wont free the allocated group if there is no purecfg.

fix this by doing the frees of new_map pointer and group pointers.

Acked-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>