crypto: caam - increase TRNG clocks per sample

we need to configure the TRNG to use more clocks per sample
to handle the two back-to-back 64KiB random descriptor requests
on higher frequency P5040s.

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