dynamic_debug: provide dynamic_hex_dump stub

The ionic driver started using dymamic_hex_dump(), but
that is not always defined:

drivers/net/ethernet/pensando/ionic/ionic_main.c:229:2: error: implicit declaration of function 'dynamic_hex_dump' [-Werror,-Wimplicit-function-declaration]

Add a dummy implementation to use when CONFIG_DYNAMIC_DEBUG
is disabled, printing nothing.

Fixes: 938962d5 ("ionic: Add adminq action")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

drivers/net/ethernet/pensando/ionic/ionic_lif.c

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2017 - 2019 Pensando Systems, Inc */
 
+#include <linux/printk.h>
+#include <linux/dynamic_debug.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/rtnetlink.h>

drivers/net/ethernet/pensando/ionic/ionic_main.c

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2017 - 2019 Pensando Systems, Inc */
 
+#include <linux/printk.h>
+#include <linux/dynamic_debug.h>
 #include <linux/module.h>
 #include <linux/netdevice.h>
 #include <linux/utsname.h>

include/linux/dynamic_debug.h

@@ -204,6 +204,12 @@ static inline int ddebug_dyndbg_module_param_cb(char *param, char *val,
 	do { if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); } while (0)
 #define dynamic_dev_dbg(dev, fmt, ...)					\
 	do { if (0) dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__); } while (0)
+#define dynamic_hex_dump(prefix_str, prefix_type, rowsize,		\
+			 groupsize, buf, len, ascii)			\
+	do { if (0)							\
+		print_hex_dump(KERN_DEBUG, prefix_str, prefix_type,	\
+				rowsize, groupsize, buf, len, ascii);	\
+	} while (0)
 #endif
 
 #endif