crypto/dpaax_sec: fix 18-bit PDCP cases with HFN override

crypto/dpaax_sec: fix 18-bit PDCP cases with HFN override

In case of RTA_SEC_ERA = 8, where the length of shared desc
is large for some of PDCP cases, the descriptor buffer cannot
hold 2 extra words when HFN override is enabled. As a result,
the descriptor fails.

This patch converts one of the keys from immediate key to
reference key hence reducing the length of the descriptor.

Fixes: 2e4cbdb4b2c2 ("crypto/dpaax_sec: support PDCP U-Plane with integrity")
Cc: stable@dpdk.org
Signed-off-by: Akhil Goyal <akhil.goyal@nxp.com>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>