[SCSI] ipr: Better handle adapter boot time errors

If an ipr adapter encounters an adapter error requiring an
adapter reset to recover from prior to driver load time, the
error will be ignored and recovery will not happen until the
initial timeout occurs waiting for the firmware to come ready,
which means a five minute timeout. Fix is to read the interrupt
register before clearing any of the interrupts at probe time.

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