Hexagon: use correct translation for VMALLOC_START

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

arch/hexagon/include/asm/mem-layout.h

@@ -72,8 +72,7 @@ extern int max_kernel_seg;
  * supposed to be based on the amount of physical memory available
  */
 
-#define VMALLOC_START (PAGE_OFFSET + VMALLOC_OFFSET + \
-	(unsigned long)high_memory)
+#define VMALLOC_START ((unsigned long) __va(high_memory + VMALLOC_OFFSET))
 
 /* Gap between physical ram and vmalloc space for guard purposes. */
 #define VMALLOC_OFFSET PAGE_SIZE