mcelog: Add the model number of Haswell server

Add the model number of Haswell Server (0x3f) to the function
select_intel_cputype, so we will not observe the error message
"mcelog: Family 6 Model 3f CPU: only decoding architectural
errors" on Haswell Server platform (Grantley platform).

Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>