rng-tools minor bug fix & enhancement update

Very small update to capture some changes that consumers may have significant interest in

Bugs fixed

• Fix compiler warning over log message format
• Fix some typos in force-reseed documentation in rngd man page

Enhancements:

• Improve --list option so that we properly capture entropy sources that are available and configured on at build time, but failed initalization at run time (due to lack of hw, or some other error, etc)

• Drop the use of libsysfs - we only used it to access a single file, and we can do so with a simple open/read/close. Given the lack of maintenance of libsysfs, we can save lots of effort by dropping this lib