[SCSI] ipr: Provide reset_adapter retry method for offlined adapters

If an ipr adapter repeatedly fails its initialization
the ipr driver will take the adapter offline and never talk
to it again. This provides a method for the user to manually
try the initialization again through sysfs.

Signed-off-by: Brian King <brking@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>