dt-bindings: Fix errors in 'if' schemas

Properties in if/then schemas weren't getting checked by the meta-schemas.
Enabling meta-schema checks finds several errors.

The use of an 'items' schema (as opposed to the list form) is wrong in
some cases as it applies to all entries. 'contains' is the correct schema
to use in the case of multiple entries.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-crypto@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-leds@vger.kernel.org
Cc: linux-mmc@vger.kernel.org
Cc: linux-gpio@vger.kernel.org
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-By: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210202205544.24812-3-robh@kernel.org