riscv: Implement benchmark log buffer

Can now perform benchmarks on the kernel using the log buffer to trace
kernel behavior.

Signed-off-by: Curtis Millar <curtis.millar@data61.csiro.au>

riscv: Map devices with large pages on 32 & 64-bit

For 64-bit, this adds a 2nd-level page table for mapping devices using
2MiB frames instead of 1GiB frames.

The boot mapping and hardware header generator have also been fixed to
correctly report the number of large frames needed for devices rather
than only reporting the first. The frame size is also specified
correctly (rather than assuming mapping with 4KiB frames).

This likely fixes an issue whereby only the first 4KiB frame of a device
was reserved but the remaining region of that kernel device could be
mapped at user level.

Signed-off-by: Curtis Millar <curtis.millar@data61.csiro.au>

Convert license tags to SPDX identifiers

This commit also converts our own copyright headers to directly use
SPDX, but leaves all other copyright header intact, only adding the
SPDX ident. As far as possible this commit also merges multiple
Data61 copyright statements/headers into one for consistency.

riscv: Add SMP data

Add data for converting logical core ID to hart ID and vice verse.

RISCV: Change 64 bit kernel window mapping to avoid PMP exception.

The SBI memory was mapped outside the kernel window. This would trigger
an instruction access fault on some hardware, when the bootloader has set
up PMP to protect the SBI memory. Instead of protecting a particular memory
region, the PMP locks the entire page table entry that covers the region.

The PADDR_LOAD and kernel base are adjusted to have the SBI memory
included in the kernel window. So that the SBI memory can be mapped as
part of the kernel image to a separate page table entry. This also
avoids the kernel to allocate untyped memory from the SBI region.

riscv: Explicit single level 2 page table

Only a single level 2 page table is now used for mapping the kernel image so this simplifies
the state data to only allocate a single PT and removes the now out of date description.

riscv: Statically determine kernel image window mapping

Uses a static check to determine whether or not we can use a single 1 GiB mapping for the
kernel image area, or if we need an additional PT.

riscv: Made two level page table for kernel mapping

This uses a one dimensional page table for the first level
and a two dimensional array for the second level such that
in a worst case scenario, the entire kernel region could
be mapped using second level tables.

Co-authored-by: Chris Guikema <chris.guikema@dornerworks.com>

Change-Id: Iad62303a0d7c2321d6038ca718888100614f91db

[SELFOUR-1156] RISC-V Port

Experimental release that supports both RV32 and RV64