pinctrl: pinctrl_select_state: set the old_state back on error

In unapply_new_state, the old state is re-applied, but p->state is not
set back as it should.

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -991,6 +991,8 @@ unapply_new_state:
 				pinmux_enable_setting(setting);
 		}
 	}
+
+	p->state = old_state;
 	return ret;
 }