audit: correct a type mismatch in audit_syscall_exit()

commit 06bdadd7634551cfe8ce071fe44d0311b3033d9e upstream.

audit_syscall_exit() saves a result of regs_return_value() in intermediate
"int" variable and passes it to __audit_syscall_exit(), which expects its
second argument as a "long" value.  This will result in truncating the
value returned by a system call and making a wrong audit record.

I don't know why gcc compiler doesn't complain about this, but anyway it
causes a problem at runtime on arm64 (and probably most 64-bit archs).

Change-Id: I6d4b429a30d9a49953d5742175dcdad3bbeb7da8
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>