pinctrl: aspeed: Rework strap register write logic for the AST2500

pinctrl: aspeed: Rework strap register write logic for the AST2500

Yong Li found that writes to the AST2500 strapping register were not
properly supported by the Aspeed pinctrl core and provided a patch to
rectify the problem. Several revisions of the patch were posted and
ultimately v4 should have been applied, however some unfortunate
liberal application of tags on my part lead to confusion between v3[1]
and v4[2].

Generate the diff between v3 and v4 to apply as a fixup patch.

[1] http://patchwork.ozlabs.org/patch/801662/
[2] http://patchwork.ozlabs.org/patch/802946/

Cc: Yong Li <sdliyong@gmail.com>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>