Print more information about MCE error whether it is an hardware or
software error.

Some of the MCE errors can be easily categorized as hardware or
software errors e.g. UEs are due to hardware error, where as error
triggered due to invalid usage of tlbie is a pure software bug. But
not all the MCE errors can be easily categorize into either software
or hardware. There are errors like multihit errors which are usually
result of a software bug, but in some rare cases a hardware failure
can cause a multihit error. In past, we have seen case where after
replacing faulty chip, multihit errors stopped occurring. Same with
parity errors, which are usually due to faulty hardware but there are
chances where multihit can also cause an parity error. Such errors are
difficult to determine what really caused it. Hence this patch
classifies MCE errors into following four categorize:

  1. Hardware error:
  	UE and Link timeout failure errors.
  2. Probable hardware error (some chance of software cause)
  	SLB/ERAT/TLB Parity errors.
  3. Software error
  	Invalid tlbie form.
  4. Probable software error (some chance of hardware cause)
  	SLB/ERAT/TLB Multihit errors.

Sample output:

  MCE: CPU80: machine check (Warning) Guest SLB Multihit DAR: 000001001b6e0320 [Recovered]
  MCE: CPU80: PID: 24765 Comm: qemu-system-ppc Guest NIP: [00007fffa309dc60]
  MCE: CPU80: Probable Software error (some chance of hardware cause)
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>