util: virpcivpd: Remove return value from virPCIVPDResourceUpdateKeyword

util: virpcivpd: Remove return value from virPCIVPDResourceUpdateKeyword

The function always succeeded and after the removal of programing error
checks doesn't even have a 'return false' case. Additionally one of the
tests in 'virpcivpdtest' tested that this function never failed on wrong
data. Embrace this logic and remove the return value and adjust logging
to VIR_DEBUG level to avoid spamming logs.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>