ARM: BCM5301X: Add DT for Meraki MR32

ARM: BCM5301X: Add DT for Meraki MR32

add support for the Cisco Meraki MR32.
This is a dual-band enterprise class 802.11ac access point.
The unit was donated by Chris Blake. Thank you!

SoC:    Broadcom BCM53016A1 (1 GHz, 2 cores)
RAM:    128 MiB
NAND:   128 MiB Spansion S34ML01G2 (~114 MiB useable)
ETH:    1GBit Ethernet Port - PoE
WIFI1:  Broadcom BCM43520 an+ac (2x2:2 - id: 0x4352)
WIFI2:  Broadcom BCM43520 bgn (2x2:2 - id: 0x4352)
WIFI3:  Broadcom BCM43428 abgn (1x1:1 - id: 43428)

BLE:    Broadcom BCM20732 (ttyS1)
LEDS:   1 x Programmable RGB Status LED (driven by a PWM)
        1 x White LED (GPIO)
        1 x Orange LED Fault Indicator (GPIO)
        2 x LAN Activity / Speed LEDs (On the RJ45 Port)
BUTTON: one Reset button
MISC:   AT24C64 8KiB EEPROM (i2c - stores Ethernet MAC)
        ina219 hardware monitor (i2c)
        Kensington Lock

SERIAL:
	WARNING: The serial port needs a TTL/RS-232 3V3 level converter!
        The Serial setting is 115200-8-N-1. The board has a populated
        right angle 1x4 0.1" pinheader.
        The pinout is: VCC, RX, TX, GND.

Odd stuff:
	- uart0 clock frequency is 62.5 MHz.
	- The LEDs are labeled as SYS-LED1 through SYS-LED3
	  because of the silkscreen on the PCB.
	- the original u-boot has been compiled with most functions
	  and commands disabled. The u-boot env isn't setup properly
	  either and as a result, the bcm47xxpart probing is not
	  working. Hence, the nand partitions are specified through a
	  "fixed-partition" binding.
	- The "WICED SMART(TM)" Bluetooth LE 4.0 BCM20732 chip is
	  connected to uart2 of the SoC. The BCM20732 does not
	  provide a HCI. So the linux' bluetooth stack is useless.
	  The mock-up node with the compatible binding and
	  enable-gpios property is provided solely as documentation.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>