macb: don't use platform_set_drvdata() on a net_device

Commit 71d64290 (Driver core: convert platform_{get,set}_drvdata to
static inline functions) now triggers a warning in the macb network
driver:

  CC      drivers/net/macb.o
drivers/net/macb.c: In function ‘macb_mii_init’:
drivers/net/macb.c:263: warning: passing argument 1 of ‘platform_set_drvdata’ from incompatible pointer type
include/linux/platform_device.h:138: note: expected ‘struct platform_device *’ but argument is of type ‘struct net_device *’

Use dev_set_drvdata() on the device embedded in the net_device instead.

Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: David S. Miller <davem@davemloft.net>