sensor: lm75: Enforce dependency of int-gpios with Trigger feature

As pointed out on #57586: `LM75_TRIGGER_GLOBAL_THREAD` can't be enabled
without the int-gpios being present in the DTS node. This commit
requires at least one LM75 instance featuring it, otherwise it won't
work.

Signed-off-by: Luis Ubieda <luisf@croxel.com>