iio: Kconfig: Provide title for IIO_TRIGGERED_EVENT symbol

For some embedded systems, a workflow involving external kernel modules
that implement IIO devices is more practical than working with in-tree
sources.

Kconfig symbols without any titles do not show up in menuconfig, and as
such are more difficult to configure granularly, as they need to be
selected by potentially unused/un-needed drivers.

Albeit, the IIO_TRIGGERED_EVENT is used by a single mainline driver, this
could allow for some out-of-tree drivers to use this kmod.

This change adds a title to the IIO_TRIGGERED_EVENT Kconfig symbol.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20200924111758.196367-3-alexandru.ardelean@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/Kconfig

@@ -63,7 +63,7 @@ config IIO_SW_TRIGGER
 	  using the API provided.
 
 config IIO_TRIGGERED_EVENT
-	tristate
+	tristate "Enable triggered events support"
 	select IIO_TRIGGER
 	help
 	  Provides helper functions for setting up triggered events.