bts: as_rsl_meas_res(): tolerate bad RxQual in early reports
Bit errors are expected during early stage of channel establishment.
Ignore bad RxQual in the very first reports (4 * 0.480s = 1.92s).
This reduces probability of sporadic failures.
Change-Id: Ie8acb15b66cd92092ec49bc8caeaf0ad4d471f1d
Related: OS#6933
