sparc: use symbolic names for tsb indexing

Use symbolic names MM_TSB_BASE and MM_TSB_HUGE instead of numeric values
0 and 1 in __tsb_context_switch.  Code cleanup only, no functional change.
Suggested-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/include/asm/mmu_context_64.h

@@ -35,15 +35,15 @@ void __tsb_context_switch(unsigned long pgd_pa,
 static inline void tsb_context_switch(struct mm_struct *mm)
 {
 	__tsb_context_switch(__pa(mm->pgd),
-			     &mm->context.tsb_block[0],
+			     &mm->context.tsb_block[MM_TSB_BASE],
 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
-			     (mm->context.tsb_block[1].tsb ?
-			      &mm->context.tsb_block[1] :
+			     (mm->context.tsb_block[MM_TSB_HUGE].tsb ?
+			      &mm->context.tsb_block[MM_TSB_HUGE] :
 			      NULL)
 #else
 			     NULL
 #endif
-			     , __pa(&mm->context.tsb_descr[0]));
+			     , __pa(&mm->context.tsb_descr[MM_TSB_BASE]));
 }
 
 void tsb_grow(struct mm_struct *mm,