target-arm: Don't mask out bits [47:40] in LPAE descriptors for v8

target-arm: Don't mask out bits [47:40] in LPAE descriptors for v8

In an LPAE format descriptor in ARMv8 the address field extends
up to bit 47, not just bit 39. Correct the masking so we don't
give incorrect results if the output address size is greater
than 40 bits, as it can be for AArch64.

(Note that we don't yet support the new-in-v8 Address Size fault which
should be generated if any translation table entry or TTBR contains
an address with non-zero bits above the most significant bit of the
maximum output address size.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1448029971-9875-1-git-send-email-peter.maydell@linaro.org