iio: pressure: mpl115: fix runtime PM leak on read error

In the Linux kernel, the following vulnerability has been resolved: iio: pressure: mpl115: fix runtime PM leak on read error mpl115_read_raw() takes a runtime PM reference with pm_runtime_get_sync() before reading the processed pressure or raw temperature, but on the read error path it returns without calling pm_runtime_put_autosuspend(). Each failed read therefore leaks a runtime PM reference and prevents the device from autosuspending. Drop the reference before checking the return value so both the success and error paths are balanced.