Rename manifest.num_vms to vm_count

Rename variable to conform to Hafnium's style guide.

Change-Id: I0b983c98eb28195bc23ba4947857d0d63a990ae3
diff --git a/src/manifest_test.cc b/src/manifest_test.cc
index fcd111d..c87acaf 100644
--- a/src/manifest_test.cc
+++ b/src/manifest_test.cc
@@ -390,7 +390,7 @@
 
 	ASSERT_TRUE(get_fdt_root(dtb_last_valid, &fdt_root));
 	ASSERT_EQ(manifest_init(&m, &fdt_root), MANIFEST_SUCCESS);
-	ASSERT_EQ(m.num_vms, 2);
+	ASSERT_EQ(m.vm_count, 2);
 	ASSERT_EQ(m.vm[1].secondary.vcpu_count, UINT16_MAX);
 
 	ASSERT_TRUE(get_fdt_root(dtb_first_invalid, &fdt_root));
@@ -430,7 +430,7 @@
 	ASSERT_TRUE(get_fdt_root(dtb, &fdt_root));
 
 	ASSERT_EQ(manifest_init(&m, &fdt_root), MANIFEST_SUCCESS);
-	ASSERT_EQ(m.num_vms, 3);
+	ASSERT_EQ(m.vm_count, 3);
 
 	vm = &m.vm[0];
 	ASSERT_STREQ(vm->debug_name, "primary_vm");