eal: make vdev init path generic for both virtual and pci devices

eal: make vdev init path generic for both virtual and pci devices

Currently, physical device pmds use a separate initalization path
(rte_pmd_init_all) while virtual devices use a constructor registration and
rte_eal_dev_init.  Theres no reason to have them be separate.  This patch
removes the vdev specific nomenclature from the vdev init path and makes it more
generic for use with all pmds.  This is the first step in converting the
physical device pmds to using the same constructor based registration path that
the virtual devices use.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>