ARM: dts: msm: increase modem size as per new memory map

Increase modem size from 139MB to 147MB on 512MB variant
as per new memory map for CV2X support.

Change-Id: I6df2eeb0cda45a3d41a789ecae2cab83a3dde813
Signed-off-by: Abinaya P <abinayap@codeaurora.org>