target-xtensa: Clean includes

Remove some include statements which are not needed.
Acked-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NStefan Weil <sw@weilnetz.de>

target-xtensa/core-dc232b.c

 #include "cpu.h"
 #include "exec-all.h"
 #include "gdbstub.h"
-#include "qemu-common.h"
 #include "host-utils.h"
 
 #include "core-dc232b/core-isa.h"

target-xtensa/core-fsf.c

 #include "cpu.h"
 #include "exec-all.h"
 #include "gdbstub.h"
-#include "qemu-common.h"
 #include "host-utils.h"
 
 #include "core-fsf/core-isa.h"

target-xtensa/helper.c

@@ -28,7 +28,6 @@
 #include "cpu.h"
 #include "exec-all.h"
 #include "gdbstub.h"
-#include "qemu-common.h"
 #include "host-utils.h"
 #if !defined(CONFIG_USER_ONLY)
 #include "hw/loader.h"