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>

drivers/base/regmap/regmap-debugfs.c

@@ -108,7 +108,8 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 			return c->base_reg;
 		}
 
-		ret = c->max;
+		*pos = c->min;
+		ret = c->base_reg;
 	}
 
 	return ret;