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.cpp b/Scope.cpp
index e7a48c6..9727ee6 100644
--- a/Scope.cpp
+++ b/Scope.cpp
@@ -47,8 +47,8 @@
     return true;
 }
 
-NamedType *Scope::lookupType(const char *name) const {
-    auto it = mTypeIndexByName.find(name);
+NamedType *Scope::lookupType(const FQName &fqName) const {
+    auto it = mTypeIndexByName.find(fqName.string().c_str());
 
     if (it != mTypeIndexByName.end()) {
         return mTypes[it->second];