staging: rts5208: Change fixed function names with "%s: ", __func__

staging: rts5208: Fix coding style issue caught by checkpatch.pl related to
function name in debug print

Signed-off-by: Gaurav Pathak <gauravpathak129@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>