ARM: dts: msm: Update TZ App region size on msm8996

On top of the original 14M memory used for TZ apps, an
additional 20M memory for Stargate apps is added into
the latest msm8996 memory map, so update TZ app region
size to be 34M, i.e. 0x2200000.

Change-Id: I9e326c016953972235346f1f0a40b1e78aea1ed8
Signed-off-by: Zhen Kong <zkong@codeaurora.org>