[SCSI] ipr: add support for multiple stages of initialization

This patch adds support for using the new IOA initialization feedback register.
It also enables 64 bit support in the ipr_ioafp_identify_hrrq and
ipr_mask_and_clear_interrupts routines.

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