sigProcLib: Slice SoftVector instead of signalVector for GMSK demod.

This makes it similar to 8-PSK demod and also saves a bit of lines ofcode and
should give us a tiny improvement in performance.

Ideally we need to remove vector slicing at all, because in osmo-bts-trx
we convert back to +-1.0 again (actually to +-127, but it doesn't mater).
So we should rather transmit +-1.0 values to avoid double conversion.

Change-Id: If9ed6f0f80fbe88c994b2f9c3cae91d0d57f4442
2 files changed