gianfar: Some cleanups for startup_gfar()

We're going to split the startup_gfar() into 3 separate functions,
so let's cleanup the code a little bit so that cosmetic changes
won't distract attention from logical ones.

- Remove needless casts (e.g. (struct sk_buff **)kmalloc());
- Turn 'unsigned long vaddr;' into 'void *vaddr', to avoid casting;
- Add new 'struct device *dev' variable as a shorthand for
  '&priv->ofdev->dev' that is used all over the place, also rename
  'struct net_device *dev' to 'struct net_device *ndev';
- Turn printk(KERN_ERR ...) to pr_err(...), which is shorter;
- Don't return bogus -1 (i.e. -EPERM) when request_irq() fails;
- Turn '&priv->regs->' to just '&regs->'.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>