Remove three redundant wrapper functions in remote.c

Remove three redundant wrapper functions in remote.c

gdb/ChangeLog:

	* remote.c (remote_mourn_1): Remove function.  Update all callers
	to use remote_mourn.
	(extended_remote_mourn_1): Remove function.  Update all callers
	to use extended_remote_mourn.
	(extended_remote_attach_1): Remove function.  Update all callers
	to use extended_remote_attach.