Replace RHOST reassing with just host

This looks okay from debug (the host looks like it's generating okay)
but there may be some subtle thing I'm not seeing here. @wchen-r7 can
you glance at this please?

[SeeRM #8498]

modules/exploits/multi/browser/java_atomicreferencearray.rb

@@ -123,7 +123,7 @@ class Metasploit3 < Msf::Exploit::Remote
           vprint_status("Sending java reverse shell")
         else
           port = datastore['LPORT']
-          datastore['RHOST'] = cli.peerhost
+          host = cli.peerhost
           vprint_status( "Java bind shell" )
         end
         if jar