[SCSI] ipr: reverse the isr optimization changes

The isr optimization patch that was submitted a few months ago
exposed problems with receiving and handling spurious HRRQ interrutps.

commit 64ffdb762241c0a9c0c8fac7ea92aa0ba1529334
Author: Wayne Boyer <wayneb@linux.vnet.ibm.com>
Date:   Wed May 19 11:56:13 2010 -0700

    [SCSI] ipr: improve interrupt service routine performance

That patch is reverted with this one.  A new patch will be submitted
once the issue is better understood and properly handled in the driver.

Signed-off-by: Wayne Boyer <wayneb@linux.vnet.ibm.com>
Acked-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>