Revert "Renamed the terse option, `cores`, to to the less-terse version `cores_per_socket`."

This reverts commit 0c37a3c68f and avoids bikeshedding from other committers.

builder/vmware/common/hw_config.go

@@ -14,7 +14,7 @@ type HWConfig struct {
 	// cpu information
 	CpuCount   int `mapstructure:"cpus"`
 	MemorySize int `mapstructure:"memory"`
-	CoreCount  int `mapstructure:"cores_per_socket"`
+	CoreCount  int `mapstructure:"cores"`
 
 	// network type and adapter
 	Network            string `mapstructure:"network"`

website/source/docs/builders/vmware-iso.html.md.erb

@@ -100,8 +100,7 @@ builder.
 
 -   `cpus` (number) - The number of cpus to use when building the VM.
 
--   `cores_per_socket` (number) - The number of cores per socket to use when
-    building the VM.
+-   `cores` (number) - The number of cores per socket to use when building the VM.
 
 -   `cdrom_adapter_type` (string) - The adapter type (or bus) that will be used
     by the cdrom device. This is chosen by default based on the disk adapter