We can use simply kmalloc() to allocate the buffers. This also simplifies the
code and allows us to perform DMA sync operations more easily.

Memory is allocated with only GFP_KERNEL since there are no DMA allocation
restrictions on this platform.
Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Tested-by: Petr Stetiar <ynezz@true.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>