detectBurst(): Clear downsampling code path
detectBurst(): Clear downsampling code path

downsampleBurst() and the Resampler below it clearly only support or are
confgiured for 1<->4 setup currently.

Change-Id: Iebaff7a34bd24e56627f148182859918accbfa82

osmocom/osmo-trx,osmocom/osmo-trx,osmocom/osmo-trx,osmocom/osmo-trx