soc: qcom: rmtfs-mem: fix memleak in probe error paths

Make sure to set the mem device release callback before calling
put_device() in a couple of probe error paths so that the containing
object also gets freed.

Fixes: d1de6d6c

 ("soc: qcom: Remote filesystem memory driver")
Cc: stable <stable@vger.kernel.org>     # 4.15
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>