rockchip: rng: add trngv1 for rk3588

rockchip: rng: add trngv1 for rk3588

This adds support for the TRNG found in the RK3588 SoC to the
rockchip_rng driver so that it can be used for things such as
seeding randomness to Linux.

Changes in V3:
 - Moved notes from commit to cover letter.
 - Added Reviewed-By tag.

Changes in V2:
 - Modified Kconfig to note that the Rockchip RNG driver supports all
   versions of the hardware (v1, v2, and the trng in the rk3588).

Signed-off-by: Lin Jinhan <troy.lin@rock-chips.com>
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>