[PATCH] ppc32: fix dma_map_page() to use page_to_bus()

The following trivial patch changes dma_map_page() to use page_to_bus()
instead of open-coding it (incorrectly in some cases).

Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
Signed-off-by: Matt Porter <mporter@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>