vbox_storage: fix coverity issue with overwriting value
vbox_storage: fix coverity issue with overwriting value

Coverity is complaining about overwriting value in 'rc' variable
without using the old value because it somehow doesn't recognize that
the value is used by MACRO. The 'rc' variable is there only for checking
return code so it's save to remove it and make coverity happy.

Signed-off-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>

VenkatDatta/libvirt,jfehlig/libvirt,eskultety/libvirt,nertpinx/libvirt,agx/libvirt,nertpinx/libvirt,crobinso/libvirt,andreabolognani/libvirt,elmarco/libvirt,eskultety/libvirt,elmarco/libvirt,elmarco/libvirt,datto/libvirt,datto/libvirt,jfehlig/libvirt,jardasgit/libvirt,taget/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,crobinso/libvirt,rlaager/libvirt,fabianfreyer/libvirt,libvirt/libvirt,VenkatDatta/libvirt,rlaager/libvirt,libvirt/libvirt,jardasgit/libvirt,zippy2/libvirt,elmarco/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,elmarco/libvirt,olafhering/libvirt,libvirt/libvirt,shugaoye/libvirt,rlaager/libvirt,nertpinx/libvirt,agx/libvirt,crobinso/libvirt,rlaager/libvirt,zippy2/libvirt,olafhering/libvirt,libvirt/libvirt,agx/libvirt,zippy2/libvirt,zippy2/libvirt,taget/libvirt,agx/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,taget/libvirt,jardasgit/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,eskultety/libvirt,eskultety/libvirt,jardasgit/libvirt,crobinso/libvirt,agx/libvirt,nertpinx/libvirt,shugaoye/libvirt,shugaoye/libvirt,olafhering/libvirt,andreabolognani/libvirt,jfehlig/libvirt,andreabolognani/libvirt,taget/libvirt,olafhering/libvirt,jfehlig/libvirt,taget/libvirt,datto/libvirt,VenkatDatta/libvirt,datto/libvirt,datto/libvirt,shugaoye/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,eskultety/libvirt,fabianfreyer/libvirt,rlaager/libvirt