at91: Add support for taskit AT91SAM9G20 boards.

This adds support for the AT91SAM9G20 boards by taskit GmbH.
Both boards, Stamp9G20 and PortuxG20, are integrated in one
file. PortuxG20 is basically a SBC built around the Stamp9G20.

Signed-off-by: Markus Hubig <mhubig@imko.de>
Cc: Andreas Bießmann <andreas.devel@googlemail.com>
Signed-off-by: Andreas Bießmann <andreas.deve@googlemail.com>
diff --git a/boards.cfg b/boards.cfg
index 6d60523..2548ca9 100644
--- a/boards.cfg
+++ b/boards.cfg
@@ -126,6 +126,8 @@
 pm9261                       arm         arm926ejs   pm9261              ronetix        at91        pm9261:AT91SAM9261
 pm9263                       arm         arm926ejs   pm9263              ronetix        at91        pm9263:AT91SAM9263
 pm9g45                       arm         arm926ejs   pm9g45              ronetix        at91        pm9g45:AT91SAM9G45
+portuxg20                    arm         arm926ejs   stamp9g20           taskit         at91        stamp9g20:AT91SAM9G20,PORTUXG20
+stamp9g20                    arm         arm926ejs   stamp9g20           taskit         at91        stamp9g20:AT91SAM9G20
 cam_enc_4xx                  arm         arm926ejs   cam_enc_4xx         ait            davinci     cam_enc_4xx
 da830evm                     arm         arm926ejs   da8xxevm            davinci        davinci
 da850_am18xxevm              arm         arm926ejs   da8xxevm            davinci        davinci     da850evm:DA850_AM18X_EVM,MAC_ADDR_IN_EEPROM,SYS_I2C_EEPROM_ADDR_LEN=2,SYS_I2C_EEPROM_ADDR=0x50