Build: Disable ECDH crypto test for profile small

This patch disables the ECDH test in the Crypto regression
for profile small which does not support the feature. The
documentation is updated accordingly in relevant places.

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I3781c473864d90ac26584b357c2903f750ed5190
8 files changed