staging: goldfish: Use __func__ instead of function name

Replace hard-coded function names in strings with "%s", __func__
in the goldfish_nand.c file. Issue found by checkpatch.pl.

Signed-off-by: Chris Coffey <cmc@babblebit.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>