sparc32,leon: Remove unnecessary page_address calls in LEON DMA API.

The function mmu_inval_dma_area takes a virtual address as a parameter
which is problematic in case the buffer is located in highmem and the
mapping currently is unavailable.

Since the function was only implemented for LEON this patch removes
calls to it in non LEON code paths and renames it to dma_make_coherent
which instead takes a physical address (which for now is unused since we
flush the whole cache). This way it is possible to remove several unnecessary
calls to page_address which will fail if the virtual mapping is unavailable.

Signed-off-by: Kristoffer Glembo <kristoffer@gaisler.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>