external/opal-prd: Use "official" switch-endian syscall
external/opal-prd: Use "official" switch-endian syscall

The "fast endian switch" syscall was never fully supported - this change
moves to the official switch-endian syscall, using __NR_switch_endian

We also form the little-endian instructions using this prepreocessor
define.

Signed-off-by: Jeremy Kerr <68a658b44bbaefab3ef5cd231967195fc0ff9d69@ozlabs.org>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

open-power/skiboot,ddstreet/skiboot,csmart/skiboot,csmart/skiboot,apopple/skiboot,shenki/skiboot,qemu/skiboot,apopple/skiboot,open-power/skiboot,legoater/skiboot,legoater/skiboot,open-power/skiboot,ddstreet/skiboot,qemu/skiboot,legoater/skiboot,shenki/skiboot,legoater/skiboot,open-power/skiboot,mikey/skiboot,legoater/skiboot,qemu/skiboot,qemu/skiboot,shenki/skiboot,qemu/skiboot,ddstreet/skiboot,stewart-ibm/skiboot,csmart/skiboot,stewart-ibm/skiboot,stewart-ibm/skiboot,mikey/skiboot,shenki/skiboot,open-power/skiboot,shenki/skiboot,mikey/skiboot,apopple/skiboot