Disabling SMP mode for certain tests was a one-release thing, done to
avoid having to triage every test independently (MANY are not
SMP-safe), and with the knowledge that it was probably hiding bugs in
the kernel.
Turn it on pervasively. Tests are treated with a combination of
flagging specific cases as "1cpu" where we have short-running tests
that can be independently run in an otherwise SMP environment, and via
setting CONFIG_MP_NUM_CPUS=1 where that's not possible (which still
runs the full SMP kernel config, but with only one CPU available).
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>