Hexagon (target/hexagon) Add overrides for dealloc-return instructions

Hexagon (target/hexagon) Add overrides for dealloc-return instructions

These instructions perform a deallocframe+return (jumpr r31)

Add overrides for
    L4_return
    SL2_return
    L4_return_t
    L4_return_f
    L4_return_tnew_pt
    L4_return_fnew_pt
    L4_return_tnew_pnt
    L4_return_fnew_pnt
    SL2_return_t
    SL2_return_f
    SL2_return_tnew
    SL2_return_fnew

This patch eliminates the last helper that uses write_new_pc, so we
remove it from op_helper.c

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20230307025828.1612809-5-tsimpson@quicinc.com>