EDAC/mc: Add new HBM2 memory type

Add a new entry to 'enum mem_type' and a new string to 'edac_mem_types[]'
for HBM2 (High Bandwidth Memory Gen 2) new memory type.

Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Muralidhara M K <muralimk@amd.com>
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20210630152828.162659-4-nchatrad@amd.com