add LDPI assets to Phone.apk

CM9 Phone app does not support LDPI screens and crashes out when used
on an LDPI device. Not sure why since the system should be able to
resize assets to the current device. This overlay fixes it by adding
LDPI assets that the system will use on such devices.

Change-Id: I8a03b9a8f40ddeaeea64050bce77932a1ce48923
Revert "u8185.mk: Increase dalvik.vm.heapsize to 76m"

This reverts commit b1347e395a82843685243829ef623c9affc0b140.

We don't need the large Dalvik heap hack now that we're using an
LDPI version of Phone.apk in our local overlay.  Thanks to kkingori
for making the low-res Phone app.