lib/reg_script: Add display support

Add the ability to enable the display of the script:
* Added REG_SCRIPT_COMMAND_DISPLAY to enable and disable display output
* Added context values to manage display support
  * display_state - Updated by the command to enable or disable display
  * display_features - May be updated by step routine to control what
    the step displays for register and value
  * display_prefix - Prefix to display before register data
* Added REG_SCRIPT_DISPLAY_ON and REG_SCRIPT_DISPLAY_OFF macros to
  control the display from the register script
* Added REG_SCRIPT_DISPLAY_REGISTER and REG_SCRIPT_DISPLAY_VALUE as
  two features of the common display.  With these features enabled
  the following is output:
  * Write: <optional prefix> register <-- value
  * Read:  <optional prefix> register --> value

TEST=Build and run on Galileo Gen2

Change-Id: If0d4d61ed8ef48ec20082b327f358fd1987e3fb9
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/14553
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

0 files changed, 0 insertions, 0 deletions