[Crash-utility] RFE: add '-l' option to dmesg command

It would be useful to have the ability to dump out only certain log levels of the kernel log. I know dmesg has '-m' which prepends the log level and then you can always use some script logic but would it be easy to add another option in crash to do this automatically? -l level Only display log messages matching 'level', which may be specified as a single number (3) or a range (0-3).