codegen: Use get_parameter_cvalue in return_out_parameter
codegen: Use get_parameter_cvalue in return_out_parameter

Using load_parameter is not needed when assigning to the same parameter.

GNOME/vala,frida/vala,spidermonkdust/vala,playya/vala,severinh/vala,kamanashisroy/aroop,flobrosch/vala-fixes,playya/vala,flobrosch/vala-fixes,Distrotech/vala,GNOME/vala,spidermonkdust/vala,jessevdk/vala,tjol/vala-tjol,frida/vala,frida/vala,xdave/pvala,rvu95/vala,tjol/vala-tjol,frida/vala,jessevdk/vala,playya/vala,GNOME/vala,kamanashisroy/aroop,severinh/vala,rvu95/vala,kamanashisroy/aroop,Distrotech/vala,tjol/vala-tjol,rvu95/vala,GNOME/vala,severinh/vala,Distrotech/vala,spidermonkdust/vala,flobrosch/vala-fixes,jessevdk/vala,frida/vala