target/riscv: Use official extension names for AIA CSRs

target/riscv: Use official extension names for AIA CSRs

The arch review of AIA spec is completed and we now have official
extension names for AIA: Smaia (M-mode AIA CSRs) and Ssaia (S-mode
AIA CSRs).

Refer, section 1.6 of the latest AIA v0.3.1 stable specification at
https://github.com/riscv/riscv-aia/releases/download/0.3.1-draft.32/riscv-interrupts-032.pdf)

Based on above, we update QEMU RISC-V to:
1) Have separate config options for Smaia and Ssaia extensions
   which replace RISCV_FEATURE_AIA in CPU features
2) Not generate AIA INTC compatible string in virt machine

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220820042958.377018-1-apatel@ventanamicro.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>