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

Change-Id: Ib7ec8ed3423e9b9b32be2388520bc27ee28f6370
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>

In order to configure and boot SCP, BL31 has to compute and send
the SHA-256 of the firmware data via scpi. Luckily Amlogic GXL SOC
has a DMA facility that could be used to offload SHA-256
computations. This adds basic support of this hardware SHA-256
engine.

Signed-off-by: Remi Pommarel <repk@triplefau.lt>