iio: light: tsl2591: return actual error from probe IRQ failure

iio: light: tsl2591: return actual error from probe IRQ failure

When devm_request_threaded_irq() fails, probe logs the error and
then returns -EINVAL, dropping the real error code and breaking the
deferred-probe flow for -EPROBE_DEFER.

Return ret directly; the IRQ subsystem already prints on failure.

Fixes: 2335f0d7c790 ("iio: light: Added AMS tsl2591 driver implementation")
Cc: stable@vger.kernel.org
Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>