soc: qcom: smem: fix qcom_smem_set_global_partition()

If there is at least one entry in the partition table, but no global
entry, the qcom_smem_set_global_partition() should return an error
just like it does if there are no partition table entries.

It turns out the function still returns an error in this case, but
it waits to do so until it has mistakenly treated the last entry in
the table as if it were the global entry found.

Fix the function to return immediately if no global entry is found
in the table.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>