staging: most: replace function name to __func__

Fix checkpatch.pl warning message about logging code. Previous code
contains hard coded function name. Fix this code by using __func__
macro.
Signed-off-by: Sidong Yang <realwakka@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/dim2/dim2.c

@@ -151,7 +151,7 @@ void dimcb_io_write(u32 __iomem *ptr32, u32 value)
  */
 void dimcb_on_error(u8 error_id, const char *error_message)
 {
-	pr_err("dimcb_on_error: error_id - %d, error_message - %s\n", error_id,
+	pr_err("%s: error_id - %d, error_message - %s\n", __func__, error_id,
 	       error_message);
 }