3c59x: Get rid of "Trying to free already-free IRQ"

Following trace pops up if we try to suspend with 3c59x ethernet NIC
brought down:

  root@b1:~# ifconfig eth16 down
  root@b1:~# echo mem > /sys/power/state
  ...
  3c59x 0000:00:10.0: suspend
  3c59x 0000:00:10.0: PME# disabled
  Trying to free already-free IRQ 48
  ------------[ cut here ]------------
  Badness at c00554e4 [verbose debug info unavailable]
  NIP: c00554e4 LR: c00554e4 CTR: c019a098
  REGS: c7975c60 TRAP: 0700   Not tainted  (2.6.31-rc4)
  MSR: 00021032 <ME,CE,IR,DR>  CR: 28242422  XER: 20000000
  TASK = c79cb0c0[1746] 'bash' THREAD: c7974000
  ...
  NIP [c00554e4] __free_irq+0x108/0x1b0
  LR [c00554e4] __free_irq+0x108/0x1b0
  Call Trace:
  [c7975d10] [c00554e4] __free_irq+0x108/0x1b0 (unreliable)
  [c7975d30] [c005559c] free_irq+0x10/0x24
  [c7975d40] [c01e21ec] vortex_suspend+0x70/0xc4
  [c7975d60] [c017e584] pci_legacy_suspend+0x58/0x100

This is because the driver manages interrupts without checking for
netif_running().

Though, there are few other issues with suspend/resume in this driver.
The intention of calling free_irq() in suspend() was to avoid any
possible spurious interrupts (see commit 5b039e68


"3c59x PM fixes"). But,

- On resume, the driver was requesting IRQ just after pci_set_master(),
  but before vortex_up() (which actually resets 3c59x chips).

- Issuing free_irq() on a shared IRQ doesn't guarantee that a buggy
  HW won't trigger spurious interrupts in another driver that
  requested the same interrupt. So, if we want to protect from
  unexpected interrupts, then on suspend we should issue disable_irq(),
  not free_irq().

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