Fix NullPointerException in BasicToPwleSegmentAdapter

We're updating the BasicToPwleSegmentAdapter to check if the FrequencyProfile is empty (has no valid frequency range) before attempting to adapt the segment. Without that there is a possibility of a NullPointerException. If the FrequencyProfile is empty, then we return the segments unchanged.

Bug: 388239434
Flag: android.os.vibrator.normalized_pwle_effects
Test: atest BasicToPwleSegmentAdapterTest
Change-Id: Ic519b1e7bf2c1319bb17fa6412e2091aa2bd1353