doc: driver-model: fix typo in design.rst

Fix the 'memeber' typo in doc/driver-model/design.rst.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/driver-model/design.rst b/doc/driver-model/design.rst
index 9e92727..96525b6 100644
--- a/doc/driver-model/design.rst
+++ b/doc/driver-model/design.rst
@@ -628,7 +628,7 @@
 bus device, regardless of its own views on the matter.
 
 The uclass for the device can also contain data private to that uclass.
-But note that each device on the bus may be a memeber of a different
+But note that each device on the bus may be a member of a different
 uclass, and this data has nothing to do with the child data for each child
 on the bus. It is the bus' uclass that controls the child with respect to
 the bus.