target/arm: Use FIELD_EX32 for testing 32-bit fields

target/arm: Use FIELD_EX32 for testing 32-bit fields

Cut-and-paste errors mean we're using FIELD_EX64() to extract fields from
some 32-bit ID register fields. Use FIELD_EX32() instead. (This makes
no difference in behaviour, it's just more consistent.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200214175116.9164-21-peter.maydell@linaro.org