iommu-helper: use bitmap library

Use bitmap library and kill some unused iommu helper functions.

1. s/iommu_area_free/bitmap_clear/

2. s/iommu_area_reserve/bitmap_set/

3. Use bitmap_find_next_zero_area instead of find_next_zero_area

  This cannot be simple substitution because find_next_zero_area
  doesn't check the last bit of the limit in bitmap

4. Remove iommu_area_free, iommu_area_reserve, and find_next_zero_area

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index fd51578..5547ae6 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -30,7 +30,7 @@
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/dma-mapping.h>
-#include <linux/bitops.h>
+#include <linux/bitmap.h>
 #include <linux/iommu-helper.h>
 #include <linux/crash_dump.h>
 #include <asm/io.h>
@@ -251,7 +251,7 @@
 	}
 
 	ppc_md.tce_free(tbl, entry, npages);
-	iommu_area_free(tbl->it_map, free_entry, npages);
+	bitmap_clear(tbl->it_map, free_entry, npages);
 }
 
 static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,