arm64: Provide default implementation for dma_{alloc,free}_attrs

Most architectures that define CONFIG_HAS_DMA, have implementations for
both dma_alloc_attrs() and dma_free_attrs().  All achitectures that do
not define CONFIG_HAS_DMA also have both of these definitions provided
by dma-mapping-broken.h.

Add default implementations for these functions on arm64.

Change-Id: I2020d18803594e6051d30f24500081de1df99fc8
Signed-off-by: Damian Hobson-Garcia <dhobsong@igel.co.jp>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-Repo: git://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/


Git-commit: d25749afc6f2a40471a70c04a35633e30cbe59a5
Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>