include/linux: printk is needed in filter.h when CONFIG_BPF_JIT is defined

for make V=1 EXTRA_CFLAGS=-W ARCH=arm allmodconfig
    printk is need when CONFIG_BPF_JIT is defined
    or it will report pr_err and print_hex_dump are implicit declaration
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/filter.h

@@ -48,6 +48,9 @@ extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
 extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len);
 
 #ifdef CONFIG_BPF_JIT
+#include <linux/linkage.h>
+#include <linux/printk.h>
+
 extern void bpf_jit_compile(struct sk_filter *fp);
 extern void bpf_jit_free(struct sk_filter *fp);