Fix VerifyCdmHost_0 export from ClearKeyCdm library

This change reverts the spanification done to the VerifyCdmHost_0
function in clear_key_cdm.cc as part of this change:
https://chromium-review.googlesource.com/c/chromium/src/+/6731994

The function signature needs to match the header file CDM_API in
content_decryption_module_ext.h to be properly exported.

Bug: 447346226
Change-Id: I1083c3679571b4aaa95f65b6d73887fbbd51109d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6986102
Commit-Queue: Nic Williamson <champnic@microsoft.com>
Reviewed-by: Sangbaek Park <sangbaekpark@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1521010}