maglev: Reduce nesting of GetLookupTable
maglev: Reduce nesting of GetLookupTable

This improves readability and slight improves performance (-0.0005sec
per GetLookupTable() invocation):

    MaglevTestSuite.BenchmarkGetMaglevTable 10 178955664 ns/op

Suggested-by: Paul Chaignon <a027184a55211cd23e3f3094f1fdc728df5e0500@cilium.io>
Signed-off-by: Martynas Pumputis <6b0d31c0d563223024da45691584643ac78c96e8@lambda.lt>

tgraf/cilium,tgraf/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,michi-covalent/cilium,tklauser/cilium,tgraf/cilium,tklauser/cilium,tklauser/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium