security: modify PDCP xform to support SDAP

security: modify PDCP xform to support SDAP

The SDAP is a protocol in the LTE stack on top of PDCP for
QOS. A particular PDCP session may or may not have
SDAP enabled. But if it is enabled, SDAP header should be
authenticated but not encrypted if both confidentiality and
integrity is enabled. Hence, the driver should be intimated
from the xform so that it skip the SDAP header while encryption.

A new field is added in the PDCP xform to specify SDAP is enabled.
The overall size of the xform is not changed, as hfn_ovrd is just
a flag and does not need uint32. Hence, it is converted to uint8_t
and a 16 bit reserved field is added for future.

Signed-off-by: Akhil Goyal <akhil.goyal@nxp.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>