AArch64: improve usage of TargetReg() and friends.

TargetReg(arg1) does now always return a 32-bit register. We also avoid
using this function directly and rather use the two-arguments overload
or TargetPtrReg().

Change-Id: I746b3c29a2a2553b399b5c3e7ee3887c7e7c52c3
diff --git a/compiler/dex/quick/mir_to_lir.h b/compiler/dex/quick/mir_to_lir.h
index 634ab94..fd0fe6e 100644
--- a/compiler/dex/quick/mir_to_lir.h
+++ b/compiler/dex/quick/mir_to_lir.h
@@ -1201,7 +1201,7 @@
      * @param wide_kind What kind of view of the special register is required.
      * @return Return the #RegStorage corresponding to the given purpose @p reg.
      *
-     * Note: For 32b system, wide (kWide) views only make sense for the argument registers and the
+     * @note For 32b system, wide (kWide) views only make sense for the argument registers and the
      *       return. In that case, this function should return a pair where the first component of
      *       the result will be the indicated special register.
      */