arm64: Limit the CMA buffer to 32-bit if ZONE_DMA

arm64: Limit the CMA buffer to 32-bit if ZONE_DMA

When the CMA buffer is allocated, it is too early to know whether
devices will require ZONE_DMA memory. This patch limits the CMA buffer
to (DMA_BIT_MASK(32) + 1) if CONFIG_ZONE_DMA is enabled.

In addition, it computes the dma_to_phys(DMA_BIT_MASK(32)) before the
increment (no current functional change).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 2d5a5612bceda8edd25b29f363c4e2c6cda28bab)
Signed-off-by: Mark Brown <broonie@kernel.org>
Conflicts:
	arch/arm64/mm/init.c