arm64: dts: qcom: Add PMI8996 DTSI file

PMI8996 is *almost* the same hardware as PMI8994, say for some annoyances:

- Boards equipped with PMI8996 now have to include pmic-id (which wasn't the
case before)

- Different qpnp-ibb-discharge-resistor value (will be addressed after LABIBB
is introduced)

- Different inhibit-derating-ua value (will be addressed after BCL is
introduced)

- Different ramp_up_step value (will be addressed after [if?] QPNP Flash LED
is introduced)

This DTSI is supposed to be included >>ON TOP OF<< pmi8994.dtsi, like this:

-- msm8996-nice-device.dts --
\#include "pmi8994.dtsi"
\#include "pmi8996.dtsi"

or more likely like this:

-- msm8996-some-phone.dts --
\#include "msm8996.dtsi"
...
\#include "pmi8994.dtsi"

-- msm8996-pmi8996-some-phone.dts --
\#include "msm8996-some-phone.dts"
\#include "pmi8996.dtsi"

So that we only have to keep 2 DTs for devices that were shipped with both
ones, instead of what would be three (device base + pmi8994 + pmi8996)

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Link: https://lore.kernel.org/r/20210608202143.247427-1-konrad.dybcio@somainline.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

arch/arm64/boot/dts/qcom/pmi8996.dtsi

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021, Konrad Dybcio <konrad.dybcio@somainline.org>
+ */
+
+ /*
+  * PMI8996 is a slight modification of PMI8994 with
+  * some notable changes, like being the first PMIC
+  * whose the bootloader has to check to continue booting
+  * and a change to a LABIBB parameter.
+  */
+
+/ {
+	qcom,pmic-id = <0x20009 0x10013 0 0>;
+};