crypto: caam - set descriptor sharing type to SERIAL

SHARE_WAIT, whilst more optimal for association-less crypto,
has the ability to start thrashing the CCB descriptor/key
caches, given high levels of traffic across multiple security
associations (and thus keys).

Switch to using the SERIAL sharing type, which prefers
the last used CCB for the SA.  On a 2-DECO platform
such as the P3041, this can improve performance by
about 3.7%.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>