ANDROID: Remove support for ZONE_DMA and ZONE_DMA32

Microdroid doesn't interact with peripherals, and therefore doesn't
have requirements for DMA'able memory. Therefore, place all memory
in ZONE_NORMAL. This avoids scenarios where memory is allocated
specifically for allocations that must be satisfied from ZONE_DMA,
such as in the coherent atomic DMA pooling code.

Bug: 432329937
Change-Id: Id29dec450edbb45d539bab2cc8e77defd8ba9ca9
Signed-off-by: Isaac J. Manjarres <isaacmanjarres@google.com>