target/hexagon: reduce scope of def_regnum, remove dead assignment

This is intended to address a coverity finding: CID 1527408.

Signed-off-by: Brian Cain <bcain@quicinc.com>
Reviewed-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Message-Id: <20240114234453.4114587-1-bcain@quicinc.com>
1 file changed