hung-chang-dso-2100: Fix a gcc 7 compiler warning.

hung-chang-dso-2100: Fix a gcc 7 compiler warning.

  ../src/hardware/hung-chang-dso-2100/api.c: In function ‘config_commit’:
  ../src/hardware/hung-chang-dso-2100/api.c:562:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
     state = 0x01;
     ~~~~~~^~~~~~
  ../src/hardware/hung-chang-dso-2100/api.c:563:2: note: here
    default:
    ^~~~~~~
  ../src/hardware/hung-chang-dso-2100/api.c:565:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
     if (ret != SR_OK)
        ^
  ../src/hardware/hung-chang-dso-2100/api.c:567:2: note: here
    case 0x01:
    ^~~~