ARM: dts: msm: Increase ADSP ion heap by 4 MB for qcs405

Increase ADSP ION heap by 4 MB that is required by the
Dynamic heap functionality.

Change-Id: I3a03740510e0dea0f5586726ff0b4c2793826a4d
Acked-by: Chenna Kesava Raju <chennak@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>