ARM: imx: Use correct SRC base address

Commit 4a4fb661 ("ARM: imx: Add missing of_node_put()") accidentally
forgot to rename a variable, which caused the wrong address to be used
and, in our case, the ULL getting falsely identified as ULZ.

Fixes: 4a4fb661 ("ARM: imx: Add missing of_node_put()")
Signed-off-by: Robert Karszniewicz <r.karszniewicz@phytec.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>