sbvarsign: remove unused global variable

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/src/sbvarsign.c b/src/sbvarsign.c
index 92475a2..bd1fc17 100644
--- a/src/sbvarsign.c
+++ b/src/sbvarsign.c
@@ -105,7 +105,6 @@
 static uint32_t attr_invalid = 0xffffffffu;
 static const char *attr_prefix = "EFI_VARIABLE_";
 
-static const EFI_GUID default_guid = EFI_GLOBAL_VARIABLE;
 static const EFI_GUID cert_pkcs7_guid = EFI_CERT_TYPE_PKCS7_GUID;
 
 static void set_default_outfilename(struct varsign_context *ctx)