dt-bindings: pinctrl: sunxi: Get rid of continual nesting

Rather than a continual nesting of 'else' clauses, just make
each 'if' a new entry under 'allOf' and get rid of the else.

Signed-off-by: Yangtao Li <frank@allwinnertech.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/229e4870dab1b34797304c384e68c7d04196423b.1595572867.git.frank@allwinnertech.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>