libvixl: fix 64bit constants usage

Since commit 999b53ec:
 Author: Claudio Fontana <claudio.fontana@linaro.org>
 Date:   Wed Feb 5 17:27:28 2014 +0000

    disas: Implement disassembly output for A64

    Use libvixl to implement disassembly output in debug
    logs for A64, for use with both AArch64 hosts and targets.

disas/libvixl/ contains functions which uses 64bit constants
without using appropriate suffixes, which fails on 32bits.

Fix this by using ULL suffix.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>