Fix test to allow >14 signal strength fields from HTC RIL.

Recent change "HTCQualcommRIL: adaptable signal strength format" broke
signal strength reporting on the HTC Evo 4G LTE (jewel); it appears
the RIL used on this device reports more than 14 fields, rather than
strictly 14 fields.  Updated the if statement accordingly.

Change-Id: Ib2324b1813e137db0b1916d90b5b6c52f879086d