m68k: macmace fixes

Fix a race condition in the transmit code, where the dma interrupt could update
the free tx buffer count concurrently and wedge the tx queue.

Fix the misuse of the rx frame status and rx frame length registers: no more
"fifo overrun" errors caused by the OFLOW bit being tested in the frame length
register (instead of the status register), and no more missed packets due to
incorrect length taken from status register (instead of the frame length
register).

Fix a panic (skb_over_panic BUG) caused by allocating and then copying an
incoming packet while the packet length register was changing.

Cut-and-paste the reset code from the powermac mace driver (mace.c), so the NIC
functions when MacOS does not initialise it (important for anyone wanting to
use the Emile boot loader).

Cut-and-paste the error counting and timeout recovery code from mace.c.

Fix over allocation of rx buffer memory (it's page order, not page count).

Converted to driver model.

Converted to DMA API.

Since I've run out of ways to make it fail, and since it performs well now,
promote the driver from EXPERIMENTAL status. Tested on both quadra 840av and
660av.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>