Report the bandwidth from adjacent signal level

Report the bandwidth from adjacent signal levels if there is no
sufficient data usage with current signal level.

Bug: 187520014
Bug: 196253433
Test: atest FrameworksTelephonyTests:com.android.internal.telephony
Change-Id: I7a1779896defa98d8d4bcd00e020555ea3bf8990
Merged-In: I7a1779896defa98d8d4bcd00e020555ea3bf8990