ARM: realview: remove old AMBA device DMA definitions

The AMBA DMA macro definitions are not used, and the AMBA Primecell DMA
support makes no use of them either, so they can be removed.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>