doc: drop old naming of the project

doc: drop old naming of the project

It was requested by Intel, more than one year ago, to replace the name
"Intel DPDK" by "DPDK".
Some references to the old name were still in some docs and code comments,
leading to confusion.

Fixes: ac8ada004c12 ("doc: remove Intel references from release notes")

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>