package/rng-tools: bump to version 6.16

- Drop patches (already in version)
- libcap is a mandatory dependency since
  https://github.com/nhorman/rng-tools/commit/50afdce9d3fed6244a0cf772d38f2d8475312bc5
- Add Qrypt support:
  https://github.com/nhorman/rng-tools/commit/7ab7f540da567467055f77016590744d828fc9eb

https://github.com/nhorman/rng-tools/releases/tag/v6.16



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>