Removed unused PING_IPV4_COMMAND etc

PING_IPV4_COMMAND, PING_IPV6_COMMAND and PING_PACKET_LOSS_REGEX had
been added since Ia34d7c75ad05f7658d1abb7bebeb1bbd271fd089 (2012),
but they were never used at all.
This patch removes them for the cleanup.

Change-Id: Ide56a0eaa6727d41fb35fb287dcf919828db05e5
1 file changed