Remove linux/mm.h inclusion from netdevice.h -- it's unused (I've checked manually).

To prevent mm.h inclusion via other channels also extract "enum dma_data_direction"
definition into separate header. This tiny piece is what gluing netdevice.h with mm.h
via "netdevice.h => dmaengine.h => dma-mapping.h => scatterlist.h => mm.h".
Removal of mm.h from scatterlist.h was tried and was found not feasible
on most archs, so the link was cutoff earlier.

Hope people are OK with tiny include file.

Note, that mm_types.h is still dragged in, but it is a separate story.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

i.MX23 Reference Manaul starts auart index from 1 than 0.  Changing
the index to start from 0 requires corresponding changes on base
address, irq, and iomux definitions, and will probably confuse people
who reads codes and hardware documents together.

This patch introduced the field 'hwid' to distinguish the driver id
and controller id.  These two ids are different on mx23 while
identical on mx28.
Signed-off-by: NShawn Guo <shawn.guo@freescale.com>
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>

Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>