ipq806x: ipq4019: add ap-dk01.1-c1 board support

ipq806x: ipq4019: add ap-dk01.1-c1 board support

AP-DK01.1-C1 is QCA dev board with:
- ipq4018 quad core ARM @716.8MHz, 2x2 dual (11n+11ac) radio
- 256MB RAM
- 32MB SPI flash
- QCA8075 multiport ethernet phy (WAN port, 4x LAN ports)

First installation via u-boot:
sf probe
sf erase 0x180000 0x1a00000
tftpboot 0x84000000 lede-ipq806x-AP-DK01.1-C1-squashfs-sysupgrade.bin
sf write 0x84000000 0x180000 $filesize

Further upgrades via sysupgrade.

Changes:
- add partitions
- set memory size to 256MB
- add reserved memory mapping
- add correct compatible string
- add image generation
- extract pre-cal data from ART partition

Compile and run tested.
Wirespeed NAT can be achieved with spreading rx interrupts over different
cores. Wifi speed is ~550Mbps @5GHz in open air.

Note:
AP-DK01.1-C1 is fully compatible with AP-DK01.2-C1, which has
ipq4028 instead of ipq4018 on board.

Changes since v2:
- based on dts(i) rework/cleanup submitted:
  http://lists.infradead.org/pipermail/lede-dev/2017-October/009596.html
- precise reserved memory mapping
- more precise description
- compatible string

Signed-off-by: Roman Yeryomin <roman@advem.lv>