librtas: Little endian support in syscalls

This patch attempts to make rtas syscalls compatible for Little
Endian systems by ensuring rtas call parameters are Big Endian and
return values are host endian.

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
librtas: avoid bashism in rules.mk

Ubuntu has made dash as its default shell (/bin/sh). This leads to build
being broken on ubuntu.
More information at: https://wiki.ubuntu.com/DashAsBinSh
This patch removes bashism and hence fixes the build breakage.

Signed-off-by: Maran Pakkirisamy <maranp@linux.vnet.ibm.com>
README: documentation on handling endianness

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Perparations for librtas-1.3.11

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>