regmap: Provide debugfs read of register ranges

If a register range is named then provide a debugfs file showing the
contents of the range separately.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 27e66c3..ac869d2 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -121,6 +121,7 @@
 struct regmap_range_node {
 	struct rb_node node;
 	const char *name;
+	struct regmap *map;
 
 	unsigned int range_min;
 	unsigned int range_max;