include/qemu/crc32c.h: Rename include guards to match filename

Signed-off-by: Will Newton <will.newton@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1393411566-24104-2-git-send-email-will.newton@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
