kunit: Don't crash if no parameters are generated

kunit: Don't crash if no parameters are generated

BugLink: https://bugs.launchpad.net/bugs/1959376
[ Upstream commit 37dbb4c7c7442dbfc9b651e4ddd4afe30b26afc9 ]

It's possible that a parameterised test could end up with zero
parameters. At the moment, the test function will nevertheless be called
with NULL as the parameter. Instead, don't try to run the test code, and
just mark the test as SKIPped.

Reported-by: Daniel Latypov <dlatypov@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>