TP-Link TL-MR3020 v3 is a pocket-size router based on MediaTek MT7628N.

This PR is based on the work of @meyergru[1], with his permission.

Specification:
- MediaTek MT7628N/N (575 Mhz)
- 64 MB of RAM
- 8 MB of FLASH
- 2T2R 2.4 GHz
- 1x 10/100 Mbps Ethernet

Flash instruction:

The only way to flash the image in TL-MR3020 v3 is to use
tftp recovery mode in U-Boot:

1. Configure PC with static IP 192.168.0.225/24 and tftp server.
2. Rename "openwrt-ramips-mt76x8-tplink_tl-mr3020-v3-squashfs-tftp-recovery.bin"
   to "tp_recovery.bin" and place it in tftp server directory.
3. Connect PC with the LAN port, press the reset button, power up
   the router and keep button pressed for around 6-7 seconds, until
   device starts downloading the file.
4. Router will download file from server, write it to flash and reboot.

[1] https://github.com/meyergru/lede-source/commits/TL-MR3020-V3

Signed-off-by: Carlo Nel <carlojnel@gmail.com>

Set the pins to the required mode via the pinmux driver. It allows to
get rid of the pinmux related code in the sd card driver.

Signed-off-by: Mathias Kresin <dev@kresin.me>

Drop the nd_sd gpio pinmux in case sdcard is used. They're mutually
exclusive and for most of the boards not even used as GPIOs.

If the pins are in sdcard mode, the pins ND_WE_N and ND_CS_N are still
GPIOs (#45 and #46).

Signed-off-by: Mathias Kresin <dev@kresin.me>

Reference the HC5661A sdhci node by label instead of by the full path.

Signed-off-by: Mathias Kresin <dev@kresin.me>

The rt3883 doesn't have a pinmux group named spi_cs1. The cs1 is part
of the pci group. The function pci-func enables the second chip select.

Signed-off-by: Mathias Kresin <dev@kresin.me>

The PCI pins need to be set to "PCI Host support one device" to allow
the use of one PCI device and flash memory.

The pci-fnc function is intended to be used if no PCI is used but
flash, nand or the codec functionality is.

Signed-off-by: Mathias Kresin <dev@kresin.me>

Based on the userspace led configuration it's quite obvious that the
4g-0 led should be used for boot status indication.

Signed-off-by: Mathias Kresin <dev@kresin.me>

Use the default-state property to express the desired led handling in
the devicetree source file instead of the userspace.

Signed-off-by: Mathias Kresin <dev@kresin.me>

All boards either have a multi colour led or a single lightpipe. It
makes it impossible to handle the LEDs individual. Change the LED
config for these boards to take it into account.

Signed-off-by: Mathias Kresin <dev@kresin.me>

- fix single spaces hidden by a tab
- replace indentation with spaces by tabs
- make empty lines empty
- drop trailing whitespace
- drop unnecessary blank lines

Signed-off-by: Mathias Kresin <dev@kresin.me>
Signed-off-by: Paul Wassi <p.wassi@gmx.at>