Usage of common.h is deprecated.

* Remove common.h from RNG drivers.
* Sort includes.
* Add time.h to sandbox driver.
* Add linux/types.h to rng.h to provide size_t.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

Changes optee_rng driver to register itself has a OP-TEE service so
that a device is bound for the driver when OP-TEE enumerates the
PTA RNG service.

Cc: Sughosh Ganu <sughosh.ganu@linaro.org>
Cc: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

Add driver for OP-TEE based Random Number Generator on ARM SoCs
where hardware entropy sources are not accessible to normal world
and the RNG service is provided by a HWRNG Trusted Application (TA).

This driver is based on the linux driver: char/hw_random/optee-rng.c

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>