ARM: omap: dma: get rid of 'p' allocation and clean up

The omap_system_dma_plat_info structure is only seven words, it's not
worth the expense of kmalloc()'ing backing store for this only to
release it later.  Note that platform_device_add_data() copies the
data anyway.  Clean up the initialisation of this structure - we don't
even need code to initialise most of this structure.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>