escc: fix another coding style nit

Fix another place with =- to be "= -".
to avoid confusion with old-style "-="
(which we also have, and needs to be fixed).
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

hw/escc.c

@@ -878,9 +878,9 @@ static void sunmouse_event(void *opaque,
     ch = -dy;
 
     if (ch > 127)
-        ch=127;
+        ch = 127;
     else if (ch < -127)
-        ch=-127;
+        ch = -127;
 
     put_queue(s, ch & 0xff);