Increasing all emulator system image sizes

Size increase in system image deemed necessary after build
breakage observed on lmp-mr1-dev due to lack of space on
MIPS system image.

All system image sizes updated to match the image size
values set in MNC-dev (avoid merge conflicts, future-proof
all images against similar breakage issues).
This image size increase takes moderate space on host
device and does not affect system image download size
(images are sparse but delivered compressed anyway).

Change-Id: I2bdeb10f2d98030a358a9bc4249ce23c432de5bd