krnl386: Don't handle %ss in fix_selector().

Loading %ss with zero isn't valid either. If %ss is invalid we have bigger
problems anyway.

Signed-off-by: Zebediah Figura <zfigura@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/krnl386.exe16/wowthunk.c

@@ -93,7 +93,6 @@ static BOOL fix_selector( CONTEXT *context )
     switch(instr[0])
     {
     case 0x07: /* pop es */
-    case 0x17: /* pop ss */
     case 0x1f: /* pop ds */
         break;
     case 0x0f: /* extended instruction */