Fix the mininum width/height size calculation while testing for window...

Fix the mininum width/height size calculation while testing for window fraction of freeform feature.

Freeform CTS test could be failed if device has low screen resolution but it has high densityDPI.
These test activities(TopRight and BottomLeft) are having small fraction but having normal mininum sizes.
for example, if device has 840x1960 resolution with 420 densityDpi then CTS test expects 210px as 25% of 840 width
but actual pixel will be 236px as result of calculation, (90dp * 420 / 160).

This patch will support different resolutions of display and let test pass.

Bug: 123009883
Test: run cts -m CtsActivityManagerDeviceTestCase -t android.server.am.ActivityManagerManifestLayoutTests#testGravityAndDefaultSizeBottomLeft --skip-preconditions

Change-Id: Ie7059bbe17ec87d148c35fd26632574ce3c02356
Signed-off-by: Mark Hong <sungmin.h@samsung.com>