soc: qcom: smem: Update max processor count

Update max processor count to reflect the number of co-processors on
SM8450 SoCs.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211201072745.3969077-5-vkoul@kernel.org