ARM: dts: msm: Enable memory allocation for diag on falcon

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

CRs-Fixed: 1079523
Change-Id: Ie96470b93d879d2c175f18aef25f3e256cd0a322
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>