accel/tcg: Fix check for page writeability in load_atomic16_or_exit

PAGE_WRITE is current writability, as modified by TB protection;
PAGE_WRITE_ORG is the original page writability.

Fixes: cdfac37be0d ("accel/tcg: Honor atomicity of loads")
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
1 file changed