ARM: OMAP: Remove cpu_is_omap usage from plat-omap/dma.c

This code will be eventually in drivers, and for the
code in the drivers we don't want to have any cpu_is_omap
usage. Those macros should be private to arch/arm/mach-omap1
and arch/arm/mach-omap2.

To fix this, let's move the define for dma_omap2plus()
to dma-omap.h, and use the existing dma_attr passed in
the platform_data as the revision registers are what they
are.

Note that we can now also remove the relative includes
introduced by the recent clean-up patches.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>