qla2xxx: Prevent probe and board_disable race

The PCI register read checking introduced in commit fe1b806f4f71
("qla2xxx: Disable adapter when we encounter a PCI disconnect") is
active during driver probe. Hold off scheduling any board removal until
the driver probe has completed. This ensures that the the board_disable
work structure is initialized and more importantly, avoids racing
qla2x00_probe_one.

Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Acked-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>