Redefine fqname in hidl-gen_y.yy

There is an inconsistency in hidl-gen_y.yy that fqname does not
mean an FQName object, but a Type object. Redefined fqname to create
an FQName object only, and rename the original fqname rule to fqtype.

This also propagates to AST::lookupType and Scope::lookupType to
take an FQName object instead of a plain string.

Test: `mma`
Test: `make hidl_test && adb sync && adb shell hidl_test`
Change-Id: I5d35192fa5fa9752b10bd9e7d339eadc5cdb78c0
diff --git a/Scope.h b/Scope.h
index f6369c6..06a7b11 100644
--- a/Scope.h
+++ b/Scope.h
@@ -33,7 +33,7 @@
 
     bool addType(NamedType *type, std::string *errorMsg);
 
-    NamedType *lookupType(const char *name) const;
+    NamedType *lookupType(const FQName &fqName) const;
 
     bool isScope() const override;