[SYCL] Do additional mostly NFC changes for reduction patch(1585)#1602

Merged

v-klochkov merged 2 commits intointel:syclfrom

v-klochkov:public_vklochkov_reduction_p2fix

Apr 30, 2020

Commits on Apr 28, 2020

[SYCL][NFC] Move the reduction command group funcs out of handler.hpp
v-klochkov
committed

Commits on Apr 29, 2020

[SYCL] Additional mostly NFC changes for reduction patch(1585)
v-klochkov
committed