staging: comedi: addi_eeprom: make the 93c76 eeprom functions static

The functions used to read the 93c76 eeprom are only used in this file.
Move them to remove the need for the forward declarations.

Also, remove some of the more obvious comments and fix a couple coding
style issues while moving the functions.

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>