net: Move prototype declaration to header file include/net/net_namespace.h from net/ipx/af_ipx.c

Move prototype declaration of function to header file
include/net/net_namespace.h from net/ipx/af_ipx.c because they are used
by more than one file.

This eliminates the following warning in net/ipx/sysctl_net_ipx.c:
net/ipx/sysctl_net_ipx.c:33:6: warning: no previous prototype for ‘ipx_register_sysctl’ [-Wmissing-prototypes]
net/ipx/sysctl_net_ipx.c:38:6: warning: no previous prototype for ‘ipx_unregister_sysctl’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index da68c9a..991dcd9 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -162,6 +162,14 @@
 struct net *get_net_ns_by_pid(pid_t pid);
 struct net *get_net_ns_by_fd(int pid);
 
+#ifdef CONFIG_SYSCTL
+void ipx_register_sysctl(void);
+void ipx_unregister_sysctl(void);
+#else
+#define ipx_register_sysctl()
+#define ipx_unregister_sysctl()
+#endif
+
 #ifdef CONFIG_NET_NS
 void __put_net(struct net *net);
 
diff --git a/net/ipx/af_ipx.c b/net/ipx/af_ipx.c
index 224d058..00b2a6d 100644
--- a/net/ipx/af_ipx.c
+++ b/net/ipx/af_ipx.c
@@ -54,17 +54,10 @@
 #include <net/sock.h>
 #include <net/datalink.h>
 #include <net/tcp_states.h>
+#include <net/net_namespace.h>
 
 #include <asm/uaccess.h>
 
-#ifdef CONFIG_SYSCTL
-extern void ipx_register_sysctl(void);
-extern void ipx_unregister_sysctl(void);
-#else
-#define ipx_register_sysctl()
-#define ipx_unregister_sysctl()
-#endif
-
 /* Configuration Variables */
 static unsigned char ipxcfg_max_hops = 16;
 static char ipxcfg_auto_select_primary;