Coverty found that the shift of TARGET_PAGE_SIZE (32-bit type) might
overflow.  Fix it by casting TARGET_PAGE_SIZE to a 64-bit type before
doing the shift (CID 1523902 and CID 1523908).

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Message-Id: <ZU6F/H8CZr3q4pP/@p100>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>