platform/chrome: cros_ec_typec: zero out stale pointers

In the Linux kernel, the following vulnerability has been resolved: platform/chrome: cros_ec_typec: zero out stale pointers `cros_typec_get_switch_handles` allocates four pointers when obtaining type-c switch handles. These pointers are all freed if failing to obtain any of them; therefore, pointers in `port` become stale. The stale pointers eventually cause use-after-free or double free in later code paths. Zeroing out all pointer fields after freeing to eliminate these stale pointers.