drivers: sensors: fix compile error due to conflicting types.

Since b2495350 (sensors: Add channel specifier) the signature of
sensor_reconfigure_read_iodev() changed, but sensor_handlers.c
apparently hasn't been updated.

Fix compile time error by updating sensor_reconfigure_read_iodev()
signature in sensor_handlers.c

Signed-off-by: Andrea Merello <andrea.merello@iit.it>