soc: qcom: smem: Support global partition

SMEM V12 creates a global partition to allocate global smem items from
instead of a global heap. The global partition has the same structure as
a private partition.

Signed-off-by: Chris Lew <clew@codeaurora.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>