staging: media: davinci_vpfe: Use __func__ instead of function name

Access current function name using __func__.
Use %s and __func__ instead of function name.
Use of predefined identifier __func__ prevents typo error in function
name in print calls.

Issue found with checkpatch.pl

Signed-off-by: Mamta Shukla <mamtashukla555@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>