arm64: dts: hisilicon: hikey960: Standardize LED labels and triggers

For all 96Boards, the following standard is used for onboard LEDs.

green:user1  default-trigger: heartbeat
green:user2  default-trigger: mmc0/disk-activity(onboard-storage)
green:user3  default-trigger: mmc1 (SD-card)
green:user4  default-trigger: none, panic-indicator
yellow:wlan  default-trigger: phy0tx
blue:bt      default-trigger: hci0-power

So lets adopt the same for HiKey960 which is one of the 96Boards
CE platform.

Since there is no trigger available for onboard-storage UFS now, user2
trigger is set to none.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>