[SCSI] ipr: add endian swap enablement for 64 bit adapters

A change in the hardware design of the chip for the new adapters changes the
default endianness of MMIO operations.  This patch adds a register definition
which when written to with a predefined value will change the endianness
back to what the driver expects.

This patch also fixes two problems found during testing.

First, the first reserved field in the ipr_hostrcb64_fabirc_desc structure only
reserved one byte.  The correct amount to reserve is 2 bytes.

Second, the reserved field of the ipr_hostrcb64_error structure only reserved
2 bytes.  The correct amount to reserve is 16 bytes.

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>