target-arm: lpae: Make t0sz and t1sz signed integers

Make t0sz and t1sz signed integers to match tsz and to make
it easier to implement support for AArch32 negative t0sz.
t1sz is changed for consistensy.

No functional change.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1445864527-14520-3-git-send-email-edgar.iglesias@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
