hostap_pci: set dev->base_addr during probe

"hostap: Protect against initialization interrupt" (which reinstated
"wireless: hostap, fix oops due to early probing interrupt")
reintroduced Bug 16111.  This is because hostap_pci wasn't setting
dev->base_addr, which is now checked in prism2_interrupt.  As a result,
initialization was failing for PCI-based hostap devices.  This corrects
that oversight.

Signed-off-by: John W. Linville <linville@tuxdriver.com>