drivers: add infrastructure for meson build

drivers: add infrastructure for meson build

Add in the top-level drivers meson.build file to start adding in building
of PMDs. Since all PMDs are built in pretty much the same way, the logic
for building each PMD, including extracting the pmdinfo, is included in the
top level build file. This means that each individual driver class only
needs to specify its default dependencies and a few naming conventions, and
each driver only needs to specify it's source files, headers, etc.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Keith Wiles <keith.wiles@intel.com>
Acked-by: Luca Boccassi <luca.boccassi@gmail.com>