driver: rng: Fix SMCCC TRNG crash

Fix a SMCCC TRNG null pointer crash due to a failed smccc feature
binding.

Fixes: 53355bb86c25 ("drivers: rng: add smccc trng driver")
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>

rng: eliminate common.h include from RNG drivers

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>

drivers: rng: add smccc trng driver

Adds random number generator driver using Arm SMCCC TRNG interface to
get entropy bytes from secure monitor. The driver registers as an
Arm SMCCC feature driver to allow PSCI driver to bind a device for
when secure monitor exposes RNG support from Arm SMCCC TRNG interface.

Cc: Sughosh Ganu <sughosh.ganu@linaro.org>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>

drivers: rng: add smccc trng driver

Adds random number generator driver using Arm SMCCC TRNG interface to
get entropy bytes from secure monitor. The driver registers as an
Arm SMCCC feature driver to allow PSCI driver to bind a device for
when secure monitor exposes RNG support from Arm SMCCC TRNG interface.

Cc: Sughosh Ganu <sughosh.ganu@linaro.org>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>