kernel.h: split out mathematical helpers

kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out
mathematical helpers.

At the same time convert users in header and lib folder to use new
header.  Though for time being include new header back to kernel.h to
avoid twisted indirected includes for existing users.

[[email protected]: fix powerpc build]
  Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Andy Shevchenko <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index 70d01ed..74be34f 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -3,7 +3,9 @@
 #define _LINUX_IOMMU_HELPER_H
 
 #include <linux/bug.h>
-#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/math.h>
+#include <linux/types.h>
 
 static inline unsigned long iommu_device_max_index(unsigned long size,
 						   unsigned long offset,