build: remove redundant libs from pkgconfig

build: remove redundant libs from pkgconfig

As explained in drivers/meson.build,
"
  For the find_library() case (but not with dependency()) we also
  need to specify the "-l" flags in pkgconfig_extra_libs variable
  too, so that it can be reflected in the pkgconfig output for
  static builds.
"

The commit e30b4e566f47 ("build: improve dependency handling")
must be followed up with this one in order to remove more
occurences of pkgconfig_extra_libs redundant with use of dependency().

Fixes: f1debd77efaf ("net/af_xdp: introduce AF_XDP PMD")
Fixes: 3c32e89f68e1 ("compress/isal: add skeleton ISA-L compression PMD")
Cc: stable@dpdk.org
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Luca Boccassi <bluca@debian.org>