OvmfPkg/HardwareInfoLib: add support for qemu vars device

Add SIMPLE_INFO for devices which only have an mmio address.
Add HardwareInfoTypeQemuUefiVars type.

While being at it remove HardwareInfoTypeMax.  Looks pointless
to have it, we never loop over the available types.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

OvmfPkg/Library/HardwareInfoLib/HardwareInfoTypesLib.h

@@ -20,9 +20,8 @@
 typedef enum {
   HardwareInfoTypeUndefined      = 0,
   HardwareInfoTypeHostBridge     = 1,
+  HardwareInfoTypeQemuUefiVars   = 2,
   HardwareInfoTypeSvsmVirtioMmio = 0x1000,
-
-  HardwareInfoTypeMax
 } HARDWARE_INFO_TYPE;
 
 //
@@ -39,6 +38,16 @@ typedef struct {
 } HARDWARE_INFO_HEADER;
 #pragma pack()
 
+//
+// used by:
+//  - HardwareInfoTypeQemuUefiVars
+//
+#pragma pack(1)
+typedef struct {
+  UINT64    MmioAddress;
+} SIMPLE_INFO;
+#pragma pack()
+
 //
 // Generic data structure to access any supported hardware type
 // resource definition
@@ -50,6 +59,7 @@ typedef struct {
   union {
     UINT8               *Raw;
     HOST_BRIDGE_INFO    *PciHostBridge;
+    SIMPLE_INFO         *SimpleDevice;
   } Data;
 } HARDWARE_INFO;
 #pragma pack()