Memset structure values to 0 before sending an IOCTL

Memset ext_ctl and v4l2_ctls structure values to 0 before processing it. If
not set, unassigned values can have garbage values and that can lead to
functional/feature failure.

CRs-Fixed: 1091284
Change-Id: Ice666cddd8e734d2d91053c30c42493315292841
1 file changed