UBIFS: fix debugging messages

Patch 56e46742e846e4de167dde0e1e1071ace1c882a5 broke UBIFS debugging messages:
before that commit when UBIFS debugging was enabled, users saw few useful
debugging messages after mount. However, that patch turned 'dbg_msg()' into
'pr_debug()', so to enable the debugging messages users have to enable them
first via /sys/kernel/debug/dynamic_debug/control, which is very impractical.

This commit makes 'dbg_msg()' to use 'printk()' instead of 'pr_debug()', just
as it was before the breakage.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: stable@kernel.org [3.0+]

fs/ubifs/debug.h

@@ -188,7 +188,10 @@ extern spinlock_t dbg_lock;
 	pr_debug("UBIFS DBG " type ": " fmt "\n", ##__VA_ARGS__)
 
 /* Just a debugging messages not related to any specific UBIFS subsystem */
-#define dbg_msg(fmt, ...)   ubifs_dbg_msg("msg", fmt, ##__VA_ARGS__)
+#define dbg_msg(fmt, ...)                                                     \
+	printk(KERN_DEBUG "UBIFS DBG (pid %d): %s: " fmt "\n", current->pid,  \
+	       __func__, ##__VA_ARGS__)
+
 /* General messages */
 #define dbg_gen(fmt, ...)   ubifs_dbg_msg("gen", fmt, ##__VA_ARGS__)
 /* Additional journal messages */