iio: st_pressure: st_accel: pass correct platform data to init

Commit 7383d44b added a pointer pdata which get set to the default
platform_data when non was defined in the device. But it did not
pass this pointer to the st_sensors_init_sensor call but still
used the maybe uninitialized platform_data from dev.

This breaks initialization when no platform_data is given and
the optional st,drdy-int-pin devicetree option is not set.

This commit fixes this.

Cc: stable@vger.kernel.org
Fixes: 7383d44b ("iio: st_pressure: st_accel: Initialise sensor platform data properly")
Signed-off-by: Michael Nosthoff <committed@heine.so>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>