fork: remove duplicate included header files

linux/sched/mm.h is included more than once.

Link: https://lkml.kernel.org/r/20220912071556.16811-1-xu.panda@zte.com.cnSigned-off-by: Xu Panda <xu.panda@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Brauner (Microsoft) <brauner@kernel.org>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kernel/fork.c

@@ -97,7 +97,6 @@
 #include <linux/scs.h>
 #include <linux/io_uring.h>
 #include <linux/bpf.h>
-#include <linux/sched/mm.h>
 
 #include <asm/pgalloc.h>
 #include <linux/uaccess.h>