net: smc911x: includecheck fix for smc911x.h

fix the following 'make includecheck' warning:

  drivers/net/smc911x.h: mach/dma.h is included more than once.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>