sh/mm: Fix pmd_t for real

Because typing is hard...

Fixes: 0862ff05 ("sh/mm: Make pmd_t similar to pte_t")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/sh/include/asm/pgtable-3level.h

@@ -28,7 +28,7 @@
 #define pmd_ERROR(e) \
 	printk("%s:%d: bad pmd %016llx.\n", __FILE__, __LINE__, pmd_val(e))
 
-typedef struct {
+typedef union {
 	struct {
 		unsigned long pmd_low;
 		unsigned long pmd_high;