[bazel] fix bitstream cache log message types
[bazel] fix bitstream cache log message types

This fixes the log messages from the bitstreams cache python script to
be of the appropriate severity level.

Signed-off-by: Timothy Trippel <77eacc84f9735d3cbb55a271710be269fc3a5818@google.com>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan