iio: trigger: stm32-timer: fix MODULE_ALIAS

modprobe can't handle spaces in aliases.

Fixes: 93fbe91b

 ("iio: Add STM32 timer trigger driver")
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Link: https://lore.kernel.org/r/20211125182850.2645424-1-hi@alyssa.is


Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>