env_flash: Disable debug print statements

env_flash: Disable debug print statements

With debug the follow is printed:
  => saveenv
  Saving Environment to Flash...
  Data to save 0x18000
  Data (start 0xfff48000, len 0x18000) saved at 0x7fe63f20
  Protect off FFF40000 ... FFF5FFFF
  Un-Protected 1 sectors
  Erasing Flash...
  . done
  Erased 1 sectors
  Writing to Flash... Restoring the rest of data to 0xfff48000 len 0x18000
  done
  Protected 1 sectors
  =>

Without debug:
  => saveenv
  Saving Environment to Flash...
  Un-Protected 1 sectors
  Erasing Flash...
  . done
  Erased 1 sectors
  Writing to Flash... done
  Protected 1 sectors
  =>

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>