soc: qcom: smp2p: Correct addressing of outgoing value

soc: qcom: smp2p: Correct addressing of outgoing value

commit 63af8e44eaa56ffe613628742a2642c4c2f1a029 upstream.

The valid_entries index should not be incremented until after we have
acquired the pointer to the value, or we will read and write data one
item off.

Fixes: 50e99641413e ("soc: qcom: smp2p: Qualcomm Shared Memory Point to Point")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>