grains/core : add hw_data support for SunOS kernel type

SmartOS / Solaris systems can now have access to useful hardware
information (from smbios command).

Note : it only works on systems which export SMBIOS table (x86
platforms, Global Zone in SmartOS...). It DOESN'T work on SPARC
platform and inside a SmartOS zone (ie. SmartMachine)
Merge pull request #5139 from virtua-network/sunos_hwdata

grains/core : add hw_data support for SunOS kernel type