On the enbw_cmc board is a KSZ8864RMN switch which needs
  configured through spi before working. This is done on
  startup from u-boot through a config file stored at an
  address specified in the "hwconfig" environment variable,
  subcommand "config".
  
  For example on the enbw_cmc board:
  
  hwconfig=switch:lan=on,pwl=off,config=0x60160000
  
  The file has the following structure:
  
  - a comment starts with a '#' or a ';' and ends with a newline
  - The switch needs for its config a reg/value pair, so we
    have two columns in the file:
      reg  : contains the register address
      value: contains a 8 bit register value
    This 2 columns are seperated through space or tab.
  
  example (minimal configuration on the enbw_cmc board):
  
  ;reg    value   comment
  ;-----------------------------------------
  0x01	0x00
  0x01	0x01    ; Start Switch with this configuration