sh: Remove config.mk for rsk7203 board

Move CONFIG_SYS_TEXT_BASE to the board's config file, and remove the
unnecessary config.mk file.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>

include/configs/rsk7203.h

diff --git a/include/configs/rsk7203.h b/include/configs/rsk7203.h
index b3feaa8..0802140 100644
--- a/include/configs/rsk7203.h
+++ b/include/configs/rsk7203.h
@@ -54,6 +54,7 @@
 #define RSK7203_FLASH_BASE_1	0x20000000	/* Non cache */
 #define RSK7203_FLASH_BANK_SIZE	(4 * 1024 * 1024)
 
+#define CONFIG_SYS_TEXT_BASE	0x0C7C0000
 #define CONFIG_SYS_LONGHELP		/* undef to save memory	*/
 #define CONFIG_SYS_PROMPT	"=> "	/* Monitor Command Prompt */
 #define CONFIG_SYS_CBSIZE	256	/* Buffer size for input from the Console */