ion: msm: Correct memory-region of_node reference counting

of_parse_phandle() is used to deduce if a memory region is
associated with a particular device. The call to of_parse_phandle()
internally increments the reference count to the memory region's
of_node, and thus, the caller should reverse that action by
decrementing it via a call to of_node_put().

Change-Id: I80a0ed843312229f277c09fe107e407118a0a473
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>