ARM: dts: msm: Enable memory allocation for diag client for 8953

The new diag client requires additional memory from hlos. This
patch caters to diag memory requirement.

CRs-Fixed: 903849
Change-Id: If9d43911b35fee216b331f06a00256041a264a38
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>