hw/riscv/opentitan: bump opentitan

hw/riscv/opentitan: bump opentitan

This patch updates the OpenTitan model to match
the specified register layout as per [1]. Which is also the latest
commit of OpenTitan supported by TockOS.

Note: Pinmux and Padctrl has been merged into Pinmux [2][3], this patch removes
any references to Padctrl. Note: OpenTitan doc [2] has not yet specified
much detail regarding this, except for a note that states `TODO: this
section needs to be updated to reflect the pinmux/padctrl merger`

[1] https://github.com/lowRISC/opentitan/blob/d072ac505f82152678d6e04be95c72b728a347b8/hw/top_earlgrey/sw/autogen/top_earlgrey_memory.h
[2] https://docs.opentitan.org/hw/top_earlgrey/doc/design/
[3] https://docs.opentitan.org/hw/ip/pinmux/doc/#overview

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20221025043335.339815-2-wilfred.mallawa@opensource.wdc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>