staging: unisys: uislib: uisqueue.c: rewrite of do_locked_client_insert
1) removed unused variables
2) fixed sparse warning of context imbalance in 'do_locked_client_insert'
different lock contexts for basic block
3) removed the call to visor_signalqueue_empty() , this function is
checking whether a signal queue is empty, but the return value
of the function is not beeing used, so it is safe to remove.