intel_avf: move bits() constructor out of fast-path
intel_avf: move bits() constructor out of fast-path

lib.bits uses pairs which is a JIT NYI, leading to split traces
and GC activity due to snapshotting.

Igalia/snabb,eugeneia/snabb,eugeneia/snabb,eugeneia/snabb,snabbco/snabb,Igalia/snabb,eugeneia/snabb,snabbco/snabb,eugeneia/snabb,Igalia/snabb,Igalia/snabb,SnabbCo/snabbswitch,SnabbCo/snabbswitch,Igalia/snabb,Igalia/snabb,eugeneia/snabb,snabbco/snabb,Igalia/snabb,snabbco/snabb,snabbco/snabb,SnabbCo/snabbswitch,eugeneia/snabb,Igalia/snabb,eugeneia/snabb,SnabbCo/snabbswitch,snabbco/snabb,snabbco/snabb,snabbco/snabb