conf: remove duplicated typedefs for virDomainSevDef

The typedefs were present twice in the header file which causes failures
with some compilers, eg FreeBSD 10 CLang:

../../src/conf/domain_conf.h:2330:33: error: redefinition of typedef 'virDomainSevDef' is a C11 feature
+[-Werror,-Wtypedef-redefinition]
typedef struct _virDomainSevDef virDomainSevDef;
                                ^
../../src/conf/domain_conf.h:145:33: note: previous definition is here
typedef struct _virDomainSevDef virDomainSevDef;
                                ^
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/conf/domain_conf.h

@@ -142,9 +142,6 @@ typedef virDomainPanicDef *virDomainPanicDefPtr;
 typedef struct _virDomainMemoryDef virDomainMemoryDef;
 typedef virDomainMemoryDef *virDomainMemoryDefPtr;
 
-typedef struct _virDomainSevDef virDomainSevDef;
-typedef virDomainSevDef *virDomainSevDefPtr;
-
 /* forward declarations virDomainChrSourceDef, required by
  * virDomainNetDef
  */