sh: Remove config.mk for ms7750se 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>
diff --git a/include/configs/ms7750se.h b/include/configs/ms7750se.h
index 9b43acb..16fb0d4 100644
--- a/include/configs/ms7750se.h
+++ b/include/configs/ms7750se.h
@@ -64,6 +64,7 @@
 /* List of legal baudrate settings for this board */
 #define CONFIG_SYS_BAUDRATE_TABLE	{ 115200, 57600, 38400, 19200, 9600 }
 
+#define CONFIG_SYS_TEXT_BASE		0x8FFC0000
 #define CONFIG_SYS_MEMTEST_START	(CONFIG_SYS_SDRAM_BASE)
 #define CONFIG_SYS_MEMTEST_END		(CONFIG_SYS_TEXT_BASE - 0x100000)