Move dma350 test suite to corstone310 example folder

Rename extra_test_suites to extra_test_suites_example to highlight that
it is a standalone example and template, instead of a folder to hold
all the extra test suites.

Move dma350_s to corstone310 example folder.

Signed-off-by: David Hu <david.hu@arm.com>
Change-Id: Iae077aad27e9c2594aed10bb07484666b3c5b2f9
13 files changed