trusty: Remove explicit page-alignment of mmap and dmabuf allocations

bionic hard codes the PAGE_SIZE macro as 4096. This is going away as
Android begins to support larger page sizes.

trusty uses PAGE_SIZE to round up the allocation size of the DMA
buffers and mmap sizes. This is not explicitly needed since the kernel
will always give you a page-aligned and page-sized multiple allocation
when allocating a dmabuf or mmap-ing.

Remove this PAGE_SIZE usage from TrustyApp, app_fuzzer, coverage,
line-coverage, modulewrapper.

Bug: 294914413
Test: Boot test on 16k device
Change-Id: Iad922e0a152cb80db2e59e696d7556602fd17d67
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>