drivers/net/wireless/prism54: fix sparse warnings: make symbols static

Fix this sparse warnings:

  drivers/net/wireless/prism54/islpci_hotplug.c:97:1: warning: symbol 'prism54_probe' was not declared. Should it be static?
  drivers/net/wireless/prism54/islpci_hotplug.c:220:1: warning: symbol 'prism54_remove' was not declared. Should it be static?
  drivers/net/wireless/prism54/islpci_hotplug.c:263:1: warning: symbol 'prism54_suspend' was not declared. Should it be static?
  drivers/net/wireless/prism54/islpci_hotplug.c:286:1: warning: symbol 'prism54_resume' was not declared. Should it be static?

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>