support/testing: standardize defconfig fragments style

support/testing: standardize defconfig fragments style

Change all defconfig fragments to take advantage of
"cf3cd4388a support/tests: allow properly indented config fragment".

Make each defconfig fragment:
 - start after a backslash;
 - be declared as a multi-line string literal;
 - be indented one level more than the variable that contains it.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>