Update hisilicon drivers to not rely on undefined overflow behaviour

This consists of ensuring that the left operand of each shift is
unsigned when the operation might overflow into the sign bit.

Change-Id: I67984b6c48c08af61e95a4dbd18047e2c3151f9a
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>
7 files changed