ARM: imx: add missing of_node_put()

Calling of_find_compatible_node() returns a node pointer with refcount
incremented. Use of_node_put() on it when done.
The patch fixes the same problem on different i.MX platforms.

Fixes: 8b88f7ef ("ARM: mx25: Retrieve IIM base from dt")
Fixes: 94b2bec1 ("ARM: imx27: Retrieve the SYSCTRL base address from devicetree")
Fixes: 3172225d ("ARM: imx31: Retrieve the IIM base address from devicetree")
Fixes: f68ea682 ("ARM: imx35: Retrieve the IIM base address from devicetree")
Fixes: ee18a715 ("ARM: imx5: retrieve iim base from device tree")
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>