Description: binder: fix incorrect calculation for num_valid
References:
 https://source.android.com/security/bulletin/2020-03-01
Notes:
Bugs:
upstream: released (v5.5-rc2) [16981742717b04644a41052570fb502682a315d2]
4.19-upstream-stable:
4.9-upstream-stable:
3.16-upstream-stable:
sid:
4.19-buster-security:
4.9-stretch-security:
3.16-jessie-security: