Hexagon: add individual register access for switch_stack

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>

arch/hexagon/include/asm/processor.h

@@ -100,12 +100,49 @@ extern unsigned long get_wchan(struct task_struct *p);
  */
 
 struct hexagon_switch_stack {
-	unsigned long long	r1716;
-	unsigned long long	r1918;
-	unsigned long long	r2120;
-	unsigned long long	r2322;
-	unsigned long long	r2524;
-	unsigned long long	r2726;
+	union {
+		struct {
+			unsigned long r16;
+			unsigned long r17;
+		};
+		unsigned long long	r1716;
+	};
+	union {
+		struct {
+			unsigned long r18;
+			unsigned long r19;
+		};
+		unsigned long long	r1918;
+	};
+	union {
+		struct {
+			unsigned long r20;
+			unsigned long r21;
+		};
+		unsigned long long	r2120;
+	};
+	union {
+		struct {
+			unsigned long r22;
+			unsigned long r23;
+		};
+		unsigned long long	r2322;
+	};
+	union {
+		struct {
+			unsigned long r24;
+			unsigned long r25;
+		};
+		unsigned long long	r2524;
+	};
+	union {
+		struct {
+			unsigned long r26;
+			unsigned long r27;
+		};
+		unsigned long long	r2726;
+	};
+
 	unsigned long		fp;
 	unsigned long		lr;
 };