Add HP Elitebook 2570p

Tested with Johan Ehnberg (johan@molnix.com)

The following is tested and confirmed working:
- backlight control
- touchpad
- USB (external, smart card, fingerprint, bluetooth, webcam, WWAN)
- touchpad
- Wi-Fi
- 2,5" SATA
- USB 3.0
- SD card
- Memory: 2+2 (matched or unmatched), 8+2, 8+8
- internal flashing from libreboot
- SeaBIOS and GRUB payloads
- Boots Devuan and Ubuntu

Untested:
- ExpressCard
- DVD
- dock
- external displays
- eSATA
- trackpoint (not present on this aftermarket keyboard)

resources/coreboot/hp2570p_16mb/board.cfg

@@ -0,0 +1,8 @@
+cbtree="default"
+romtype="normal"
+arch="x86_64"
+payload_grub="y"
+payload_grub_withseabios="y"
+payload_seabios="y"
+payload_memtest="y"
+grub_scan_disk="ahci"