target-arm: Allow 3reg_wide undefreq to encode more bad size options

target-arm: Allow 3reg_wide undefreq to encode more bad size options

The current undefreq field in the neon_3reg_wide handling allows us
to encode "UNDEF if size != 0" and "UNDEF if size == 0". This is
no longer sufficient with the advent of 64-bit polynomial VMULL,
which means we want to UNDEF if size == 1. Change the undefreq
encoding to use separate bits for all of "UNDEF if size == 0",
"UNDEF if size == 1" and "UNDEF if size == 2".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1401386724-26529-3-git-send-email-peter.maydell@linaro.org