xen/arm: Throw messages for unknown FP/SIMD implement ID

xen/arm: Throw messages for unknown FP/SIMD implement ID

Arm ID_AA64PFR0_EL1 register provides two fields to describe CPU
FP/SIMD implementations. Currently, we exactly know the meaning of
0x0, 0x1 and 0xf of these fields. Xen treats value < 8 as FP/SIMD
features presented. If there is a value 0x2 bumped in the future,
Xen behaviors for value <= 0x1 can also take effect. But what Xen
done for value <= 0x1 may not always cover new value 0x2 required.
We throw these messages to break the silence when Xen detected
unknown FP/SIMD IDs to notice user to check.

Signed-off-by: Wei Chen <wei.chen@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>