doc: announce API change in crypto driver allocation

doc: announce API change in crypto driver allocation

rte_cryptodev_allocate_driver() function gets one parameter
(rte_driver), as the cryptodev_driver structure is
allocated inside the function with rte_malloc.

This function is called from a constructor function,
when crypto PMDs are registered.
If malloc fails, there is no way to recover from it,
so it is better to allocate this structure
statically, in each PMD.

Therefore, it is required to add an extra parameter in
this function, to also get a pointer to this structure.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>
Acked-by: Deepak Kumar Jain <deepak.k.jain@intel.com>