Azure/GitLab: Move to gcc-11.1.0 and LLVM-11

- Move to gcc-11.1.0 builds from kernel.org for supported platforms and
  LLVM-11 for those tests.
- As Heinrich has noted, the RISC-V platform specification has a profile
  OS-A for running rich operating systems like Linux and BSD. This profile
  requires 64bit and UEFI conforming to the EBBR. Only the 'embedded'
  profile may use 32bit.  Given this, drop grub for 32bit RISC-V as it no
  longer compiles with gcc-11.1 and upstream is unlikely to fix it:
  https://www.mail-archive.com/grub-devel@gnu.org/msg30736.html


- Update to grub-2.06 release to address other issues of building with
  gcc-11.1.
- Update to newer Xtensa (gcc-9.2.0) and ARC (gcc-10.2) toolchains

Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Rick Chen <rick@andestech.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>