arm: atmel: remove the config.mk file

remove the config.mk file
move text base define to board config file for following boards
  - at91sam9m10g45ek
  - at91sam9x5ek

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/include/configs/at91sam9m10g45ek.h b/include/configs/at91sam9m10g45ek.h
index 2aea555..fc4ecec 100644
--- a/include/configs/at91sam9m10g45ek.h
+++ b/include/configs/at91sam9m10g45ek.h
@@ -13,6 +13,8 @@
 
 #include <asm/hardware.h>
 
+#define CONFIG_SYS_TEXT_BASE		0x73f00000
+
 #define CONFIG_AT91_LEGACY
 #define CONFIG_ATMEL_LEGACY		/* required until (g)pio is fixed */