dynamic_debug: Add __dynamic_dev_dbg

Unlike dynamic_pr_debug, dynamic uses of dev_dbg can not
currently add task_pid/KBUILD_MODNAME/__func__/__LINE__
to selected debug output.

Add a new function similar to dynamic_pr_debug to
optionally emit these prefixes.

Cc: Aloisio Almeida <aloisio.almeida@openbossa.org>
Noticed-by: Aloisio Almeida <aloisio.almeida@openbossa.org>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/base/core.c b/drivers/base/core.c
index bc8729d..82c8654 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1764,8 +1764,8 @@
 
 #ifdef CONFIG_PRINTK
 
-static int __dev_printk(const char *level, const struct device *dev,
-			struct va_format *vaf)
+int __dev_printk(const char *level, const struct device *dev,
+		 struct va_format *vaf)
 {
 	if (!dev)
 		return printk("%s(NULL device *): %pV", level, vaf);
@@ -1773,6 +1773,7 @@
 	return printk("%s%s %s: %pV",
 		      level, dev_driver_string(dev), dev_name(dev), vaf);
 }
+EXPORT_SYMBOL(__dev_printk);
 
 int dev_printk(const char *level, const struct device *dev,
 	       const char *fmt, ...)