fix(spm): stop spm from being built for in aarch32

Hafnium does not support Aarch32 therefore we do not want to build
in this case. Move spm related test helpers into their own file
and add FF-A tests to the aarch32_tests_to_skip.txt file

Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
Change-Id: Ic5a83ddf4aae2b7dd4b1c30e4cc76b0447e5b405
21 files changed