backend: add sqrt-div pattern to instruction select
backend: add sqrt-div pattern to instruction select

there some patterns like:
  sqrt r1, r2;
  load r4, 1.0;       ===> rqrt r3, r2
  div r3, r4, r1;

Signed-off-by: rander.wang <5299db4a9bf784920a3e558099f6736bcd8939e6@intel.com>
Reviewed-by: Pan Xiuli <e5a665b1e626c5dc0826076a8b5a209eb48bf6ee@intel.com>

wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet