This patch fixes a crash on some systems that happens randomly when loading hostap_cs driver (for prism2/2.x/3 wireless pcmcia cards).

The problem happens on systems that assign an irq to the device that is shared with another device.
If an interrupt happens when the driver is not initialized yet system crashes.

The patch creates a poor man's semaphore to prevent ISR from executing until the driver is initialized.
There should be a more elegant solution, and still may crash if you have several prism cards at the same time, but it works for me...

Good luck!