Hexagon: switch to using the device type for IO mappings

Uncached on our architecture can still have side effects
such as canceled/replayed transactions; device type prevents
this.

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

arch/hexagon/include/asm/vm_mmu.h

@@ -68,14 +68,13 @@
 
 #define __HEXAGON_C_WB		0x0	/* Write-back, no L2 */
 #define	__HEXAGON_C_WT		0x1	/* Write-through, no L2 */
-#define	__HEXAGON_C_DEV		0x4	/* Device register space */
-#define	__HEXAGON_C_WT_L2	0x5	/* Write-through, with L2 */
-/* this really should be #if CONFIG_HEXAGON_ARCH = 2 but that's not defined */
-#if defined(CONFIG_HEXAGON_COMET) || defined(CONFIG_QDSP6_ST1)
-#define __HEXAGON_C_UNC		__HEXAGON_C_DEV
-#else
 #define	__HEXAGON_C_UNC		0x6	/* Uncached memory */
+#if CONFIG_HEXAGON_ARCH_VERSION >= 2
+#define	__HEXAGON_C_DEV		0x4	/* Device register space */
+#else
+#define __HEXAGON_C_DEV		__HEXAGON_C_UNC
 #endif
+#define	__HEXAGON_C_WT_L2	0x5	/* Write-through, with L2 */
 #define	__HEXAGON_C_WB_L2	0x7	/* Write-back, with L2 */
 
 /*