ARM: imx3: Remove unneeded #include <linux/pinctrl/machine.h>

Commit 6c5f05a6 ("ARM: imx3: Remove imx3 soc_init()")
removed the last user of the pinctrl machine API.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>