Compress lines for immediate return

Compress two lines into a single line if immediate return statement is found.

It also remove variables progress, val, data, ret and sock
as they are no longer needed.

Remove space between function "mixer_load" and '(' to fix the
checkpatch.pl error:-
ERROR: space prohibited between function name and open parenthesis '('

Done using following coccinelle script:
@@
local idexpression ret;
expression e;
@@

-ret =
+return
     e;
-return ret;

Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200401165314.GA3213@simran-Inspiron-5558>
[lv: in handle_aiocb_write_zeroes_unmap() move "int ret" inside the #ifdef]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

migration/ram.c

@@ -2135,9 +2135,7 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms)
     }
     trace_ram_postcopy_send_discard_bitmap();
 
-    ret = postcopy_each_ram_send_discard(ms);
-
-    return ret;
+    return postcopy_each_ram_send_discard(ms);
 }
 
 /**