Ath5k: suspend/resume fixes

- free and re-request irq since it might have changed during suspend
- disable and enable msi
- don't set D0 state of the device, it's already done by the PCI layer
- do restore_state before enable_device, it's safer
- check ath5k_init return value

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Cc: Luis R. Rodriguez <mcgrof@gmail.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>