regmap: debugfs: Fix attempts to read nonexistant register blocks

Return the start of the last block we tried to read rather than a position,
and also make sure we update the byte position while we're at it.  Without
this reads that go into nonexistant areas get confused.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 07aad78..43d51dc 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -108,7 +108,8 @@
 			return c->base_reg;
 		}
 
-		ret = c->max;
+		*pos = c->min;
+		ret = c->base_reg;
 	}
 
 	return ret;