pinctrl: sunxi: Fix incorrect NULL check

*map should be tested for NULL instead of map as kmalloc pointer
is assigned to it. This also fixes a potential null pointer dereference
bug later in the code.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>