Use a boundary of zero, hence a PAGE_SIZE boundary
is implied by all memory allocations.
Background:
Busdma has problems to allocate more than PAGE_SIZE
bytes when the boundary is PAGE_SIZE bytes too.
Initially it was thought that a boundary of PAGE_SIZE
bytes will only affect loading of DMA memory, so that
segments get split correctly, but it also affects
allocation of DMA'able memory.
Solution:
USB can detect big segments and split them as required
by the USB code.
MFC after: 1 week
Reported by: gonzo
1a7c3e9097