plat/arm: juno: Condition Juno entropy source with CRC instructions

The Juno Trusted Entropy Source has a bias, which makes the generated
raw numbers fail a FIPS 140-2 statistic test.

To improve the quality of the numbers, we can use the CPU's CRC
instructions, which do a decent job on conditioning the bits.

This adds a *very* simple version of arm_acle.h, which is typically
provided by the compiler, and contains the CRC instrinsics definitions
we need. We need the original version by using -nostdinc.

Change-Id: I83d3e6902d6a1164aacd5060ac13a38f0057bd1a
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
3 files changed