[SCSI] ipr: Stop reading adapter dump prematurely

When the ipr driver decides to dump the adapter, it changes the
sdt_state to GET_DUMP, then prepares the adapter so that the dump
can be read. However, if the ipr worker thread wakes up for some
reason before the driver has put the adapter in a state where it
can succesfully dump the adapter, the driver will start dumping
the adapter too early, which can potentially trigger a BUG check
in the pci config blocking API. Fix this by adding a new
sdt_state to differentiate between the ipr driver wanting to dump
the adapter in the near future and wanting to dump the adapter now.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>