xlat lib: Fix some types

Fix the type length and signedness of some of the constants and
variables used in the translation table library.

This patch supersedes Pull Request #1018:
https://github.com/ARM-software/arm-trusted-firmware/pull/1018

Change-Id: Ibd45faf7a4fb428a0bf71c752551d35800212fb2
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
7 files changed