test/py: skip tests that require large CONFIG_SYS_MAXARGS

test_hush_if_test.py executes commands that require large values of
CONFIG_SYS_MAXARGS. Detect cases where the configured value is too low
and skip those tests.

Ideally, this would be implemented inside console.run_command(). However,
the command passed to that function is already a completely formed string,
and determining its argument count usage would require splitting commands
at ;, handling quoting to deal with arguments containing spaces, etc. Even
passing the command as a list wouldn't solve all these issues, since we'd
still need to split commands on ; and deal with cases like "if test ..."
which consumes 0 of the argument count.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Simon Glass <sjg@chromium.org>