[sanitizer][fuzzer] Transition back to ZX_TIME_INFINITE

Now that all Zircon calls have been transitioned to take time as signed
value, we can transition back to ZX_TIME_INFINITE, undoing the change
made in r337802.

Differential Revision: https://reviews.llvm.org/D51266

llvm-svn: 340764
GitOrigin-RevId: 118dc299f9e524533359c694176f568fdfba2fc6
1 file changed