[NET] smc91x: fix PXA DMA support code

The PXA DMA support code for smc91x doesn't pass a struct device to
the dma_*map_single() functions, which leads to an oops in the dma
bounce code.  We have a struct device which was used to probe the
SMC chip.  Use it.

(This patch is slightly larger because it requires struct smc_local
to move into the header file.)

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>