dalvik: rework 3 and 4-GB dalvik heap configurations

The previous configuration sets target utilization as .25, which is geared towards
low memory devices. This path increases it to .75 and makes us pass the check:
(heaptargetutilization / 2) * heapsize = heapgrowthlimit

Example:
heapgrowthlimit: 256m
heapsize: 512m
heaptargetutilization: 0.75
0.75/2 * 512 = 192

To pass the check this has to be true:

192 = 256 (WRONG)

Check not passed.

This new configuration is optimized for higher RAM devices and passes the check:

heapgrowthlimit: 384m
heapsize: 1024m
heaptargetutilization: 0.75

0.75/2 * 1024 = 384

384 = 384 (TRUE)

Check passed.

Change-Id: I6839339382229da80546761c3746a032081ff2cd
Signed-off-by: Alex Naidis <alex.naidis@linux.com>