UBI: fix debugging messages

Patch ab50ff684707031ed4bad2fdd313208ae392e5bb broke UBI debugging messages:
before that commit when UBI debugging was enabled, users saw few useful
debugging messages after attaching an MTD device. 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+]

drivers/mtd/ubi/debug.h

@@ -43,7 +43,10 @@
 	pr_debug("UBI DBG " type ": " fmt "\n", ##__VA_ARGS__)
 
 /* Just a debugging messages not related to any specific UBI subsystem */
-#define dbg_msg(fmt, ...) ubi_dbg_msg("msg", fmt, ##__VA_ARGS__)
+#define dbg_msg(fmt, ...)                                    \
+	printk(KERN_DEBUG "UBI DBG (pid %d): %s: " fmt "\n", \
+	       current->pid, __func__, ##__VA_ARGS__)
+
 /* General debugging messages */
 #define dbg_gen(fmt, ...) ubi_dbg_msg("gen", fmt, ##__VA_ARGS__)
 /* Messages from the eraseblock association sub-system */