staging: comedi: cb_pcidas: remove forward declarations 9

Move the nvram_read function, and its helper, to remove the need
for the last of the forward declarations.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>