dt-bindings: Cleanup standard unit properties

Properties with standard unit suffixes already have a type and don't need
type definitions. They also default to a single entry, so 'maxItems: 1'
can be dropped.

adi,ad5758 is an oddball which defined an enum of arrays. While a valid
schema, it is simpler as a whole to only define scalar constraints.

Cc: Jean Delvare <jdelvare@suse.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Serge Semin <fancer.lancer@gmail.com>
Cc: linux-hwmon@vger.kernel.org
Cc: linux-i2c@vger.kernel.org
Cc: linux-iio@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-input@vger.kernel.org
Cc: linux-mmc@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-rtc@vger.kernel.org
Cc: linux-serial@vger.kernel.org
Cc: alsa-devel@alsa-project.org
Cc: linux-watchdog@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Wolfram Sang <wsa@kernel.org> # for I2C
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Sebastian Reichel <sre@kernel.org> # for power-supply
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> #for-iio
Acked-by: Alexandre TORGUE <alexandre.torgue@foss.st.com>
Link: https://lore.kernel.org/r/20210128194515.743252-1-robh@kernel.org