[PATCH v2] arm64: qcom: sbc: Name GPIO lines

This names the GPIO lines on the APQ8016 "SBC" also known
as the DragonBoard 410c, according to the schematic. This
is necessary for a conforming userspace looking across
all GPIO chips for the GPIO lines named "GPIO-A" thru
"GPIO-L".

Signed-off-by: Linus Walleij <redacted>
---
ChangeLog v1->v2:
- Put the GPIO line names into the .dtsi file for the
  SBC as requested.
- Put the GPIO line names into the hierarchical SoC
  DTS structure as requested.
- Adjusted legend text to only cover used terminology.
- Insert proper comments telling which line on the LSEC
  or HSEC a certain line is routed to.

I don't have this hardware available, you can test it
easily by compiling tools/gpio/* and issue "lsgpio" to
see the GPIO line names in the console.
---
 arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi | 169 ++++++++++++++++++++++++++++++
 1 file changed, 169 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi b/arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi