examples/quota_watermark: correct code indentation

examples/quota_watermark: correct code indentation

The code indentation in the example app files used spaces rather than
tabs for indentation, and as such did not conform to DPDK conventions.
This left those modifying the code in a bind - to fix things on a line
by line basis so as to avoid checkpatch errors, or to keep things
consistent within the file, and accept checkpatch errors.

Since these files have not had too many changes since the original
import, there is little change history to lose by doing a complete
reformatting of the code, so just update all indentation to standard.
In the process, wrap long lines appropriately, avoiding splitting
error messages.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>