Add virtio-transport option and deprecate force-pci and virtio-legacy.

This is a follow-up patch for [0] which proposed the --force-pci option
for riscv. As per the discussion it was concluded to add virtio-tranport
option taking in four options (pci, pci-legacy, mmio, mmio-legacy).

With this change force-pci and virtio-legacy are both deprecated and
arm's default transport changes from MMIO to PCI as agreed in [0].
This is also true for riscv.

Nothing changes for other architectures.

[0]: https://lore.kernel.org/all/20230118172007.408667-1-rkanwal@rivosinc.com/

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Link: https://lore.kernel.org/r/20230320143344.404307-1-rkanwal@rivosinc.com
Signed-off-by: Will Deacon <will@kernel.org>
16 files changed