kvargs: remove driver name in arguments

kvargs: remove driver name in arguments

Now that rte_kvargs is a generic library, there is no need to have an argument
for the driver name in rte_kvargs_tokenize() and rte_kvargs_parse()
prototypes. This argument was only used to log the driver name in case of
error. Instead, we can add a log in init function of pmd_pcap and pmd_ring.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>