printk.c: fix kernel-doc warnings

Fix kernel-doc warnings in printk.c: use correct parameter name.

  Warning(kernel/printk.c:2429): No description found for parameter 'buf'
  Warning(kernel/printk.c:2429): Excess function parameter 'line' description in 'kmsg_dump_get_buffer'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/printk.c

@@ -2538,7 +2538,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
  * kmsg_dump_get_buffer - copy kmsg log lines
  * @dumper: registered kmsg dumper
  * @syslog: include the "<4>" prefixes
- * @line: buffer to copy the line to
+ * @buf: buffer to copy the line to
  * @size: maximum size of the buffer
  * @len: length of line placed into buffer
  *