selinux: print leading 0x on ioctlcmd audits

ioctlcmd is currently printing hex numbers, but their is no leading
0x. Thus things like ioctlcmd=1234 are misleading, as the base is
not evident.

Correct this by adding 0x as a prefix, so ioctlcmd=1234 becomes
ioctlcmd=0x1234.

Signed-off-by: William Roberts <william.c.roberts@intel.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>