OBI CUT: sbr_port_rsp_o.gnt stuck at 1

[luca24balboni]

sbr_port_rsp_o.gnt of obi_cut module directly connected to ready_o port of spill_register causes protocol violation because it can be asserted even when there is no request on sbr_port_req_i port.

Fix proposed in PR #31.

[alenad95]

Closing this issue since the behavior of the grant signal coming from the CUT is compliant to the OBI protocol.