video: fbdev: Fix wrong file path for pvr2fb.c in Kconfig help text

pvr2fb.c should be under drivers/video/fbdev/
instead of drivers/video/

Signed-off-by: Wei Ming Chen <jj251510319013@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Helge Deller <deller@gmx.de>