target/arm: Make '-cpu max' have a 48-bit PA

target/arm: Make '-cpu max' have a 48-bit PA

QEMU supports a 48-bit physical address range, but we don't currently
expose it in the '-cpu max' ID registers (you get the same range as
Cortex-A57, which is 44 bits).

Set the ID_AA64MMFR0.PARange field to indicate 48 bits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201001160116.18095-1-peter.maydell@linaro.org