hpsa: refine the pci enable/disable handling

hpsa: refine the pci enable/disable handling

When a second(kdump) kernel starts and the hard reset method is used
the driver calls pci_disable_device without previously enabling it,
so the kernel shows a warning -
[   16.876248] WARNING: at drivers/pci/pci.c:1431 pci_disable_device+0x84/0x90()
[   16.882686] Device hpsa
disabling already-disabled device
...
This patch fixes it, in addition to this I tried to balance also some other pairs
of enable/disable device in the driver.
Unfortunately I wasn't able to verify the functionality for the case of a sw reset,
because of a lack of proper hw.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Reviewed-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>