leds: led-test: Remove standard error checking after KUNIT_ASSERT_*()

If a KUNIT_ASSERT_*() call ends up in an assertion, the test is marked
as a failure and the subsequent error checking is never executed, making
it superfluous.  Remove it for simplicity and to avoid confusion.

Link: https://lore.kernel.org/r/20250501081918.3621432-1-lee@kernel.org


Signed-off-by: Lee Jones <lee@kernel.org>