arm64: dts: apple: Add A8X devices

arm64: dts: apple: Add A8X devices

Add DTS files for the A8X SoC and the only device based on it, the iPad
Air 2.

Signed-off-by: Konrad Dybcio <konradybcio@kernel.org>
[Markuss: System memory bits]
Co-developed-by: Markuss Broks <markuss.broks@gmail.com>
Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
[Nick: SMP, m1n1 and gpio-keys support, pinctrl fixes]
Co-developed-by: Nick Chan <towinchenmi@gmail.com>
Signed-off-by: Nick Chan <towinchenmi@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Hector Martin <marcan@marcan.st>