dts: arm: nordic: fix cryptocell description

The ARM Cryptocell 310/312 IP is wrapped by Nordic specific registers.
It is organized as follows:

- Base address: Nordic wrapper
- Base address + 0x1000: ARM Cryptocell IP registers

Following more standard devicetree conventions, use a single node for
what is exposed as a single peripheral. The node contains 2 register
entries, one for the wrapper and a second one for the 3rd party IP.
Compatibles are used from more specific (nordic,cryptocell) to more
generic (arm,cryptocell-3xx).

Other minor fixes: peripheral is disabled by default (as it should be in
SoC dts files).

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>