qualcommax: ipq807x: fix LEDs on QNAP QHora-301W

qualcommax: ipq807x: fix LEDs on QNAP QHora-301W

On QNAP QHora-301W, all LEDs don't have "function" property and only
"color" property is available for the newer binding of LED on Linux
Kernel.
2e659930d3 ("qualcommax: drop redundant label with new LED
color/function format") removes "label" property from LEDs, then,
multiple "<color>:" (ex.: "amber:"/"green:"/"red:") will be appeared as
LED names and renamed to "<color>:_<num>" ("ex.: "green:_1", "green:_2",
...) by kernel.

logs:

[    4.246494] leds-gpio leds: Led green: renamed to green:_1 due to name collision
[    4.248978] leds-gpio leds: Led green: renamed to green:_2 due to name collision
[    4.256345] leds-gpio leds: Led green: renamed to green:_3 due to name collision
[    4.263770] leds-gpio leds: Led green: renamed to green:_4 due to name collision
[    4.271105] leds-gpio leds: Led amber: renamed to amber:_1 due to name collision
[    4.278487] leds-gpio leds: Led green: renamed to green:_5 due to name collision
[    4.285856] leds-gpio leds: Led amber: renamed to amber:_2 due to name collision
[    4.293257] leds-gpio leds: Led green: renamed to green:_6 due to name collision
[    4.300616] leds-gpio leds: Led amber: renamed to amber:_3 due to name collision
[    4.308002] leds-gpio leds: Led green: renamed to green:_7 due to name collision
[    4.315384] leds-gpio leds: Led amber: renamed to amber:_4 due to name collision
[    4.322760] leds-gpio leds: Led green: renamed to green:_8 due to name collision
[    4.330135] leds-gpio leds: Led amber: renamed to amber:_5 due to name collision

/sys/class/leds:

amber:          amber:_4        green:_2        green:_6
amber:_1        green:_5        green:_3        green:_7
amber:_2        green:          green:_4        green:_8
amber:_3        green:_1        green:_5        red:

Fix this issue by adding missing "function" (and "function-enumerator")
property to LEDs on QNAP QHora-301W.
Note: there are no appropriate functions in dt-bindings/leds/common.h
for some LEDs, so use the hardcoded strings for them instead.

Fixes: 2e659930d3 ("qualcommax: drop redundant label with new LED color/function format")
Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>