collectd: remove the patch scaling ping_droprate from 0-1 to 0-100

collectd: remove the patch scaling ping_droprate from 0-1 to 0-100

Upstream project's behaviour of reporting this data source in range 0-1
is used by at least CentOS 7 collectd 5.8.1, very likely the same
behaviour is also in widely use by other distributions.

The change is important for providing consistent experience across
collectd deployments on different environments

Ref: https://github.com/collectd/collectd/pull/3244
Signed-off-by: Yousong Zhou <redacted>