hw/riscv: opentitan: bump opentitan version

hw/riscv: opentitan: bump opentitan version

The following patch updates opentitan to match the new configuration,
as per, lowRISC/opentitan@217a0168ba118503c166a9587819e3811eeb0c0c

Note: with this patch we now skip the usage of the opentitan
`boot_rom`. The Opentitan boot rom contains hw verification
for devies which we are currently not supporting in qemu. As of now,
the `boot_rom` has no major significance, however, would be good to
support in the future.

Tested by running utests from the latest tock [1]
(that supports this version of OT).

[1] https://github.com/tock/tock/pull/3056

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220812005229.358850-1-wilfred.mallawa@opensource.wdc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>