target/riscv/kvm: clarify how 'riscv-aia' default works

target/riscv/kvm: clarify how 'riscv-aia' default works

We do not have control in the default 'riscv-aia' default value. We can
try to set it to a specific value, in this case 'auto', but there's no
guarantee that the host will accept it.

Couple with this we're always doing a 'qemu_log' to inform whether we're
ended up using the host default or if we managed to set the AIA mode to
the QEMU default we wanted to set.

Change the 'riscv-aia' description to better reflect how the option
works, and remove the two informative 'qemu_log' that are now unneeded:
if no message shows, riscv-aia was set to the default or uset-set value.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241028182037.290171-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit fd16cfb2995e9196b579d8885145c4247dfa6058)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>