m68k: rename CONFIG_MCFTMR to CFG_MCFTMR

This is not a Kconfig option so changing to _CFG.

Signed-off-by: Angelo Durgehello <angelo@kernel-space.org>
diff --git a/include/configs/amcore.h b/include/configs/amcore.h
index 37c45e7..35f09b4 100644
--- a/include/configs/amcore.h
+++ b/include/configs/amcore.h
@@ -10,7 +10,7 @@
 
 #define CFG_SYS_UART_PORT		0
 
-#define CONFIG_MCFTMR
+#define CFG_MCFTMR
 #define CONFIG_MCFUART
 #define CONFIG_SYS_UART_PORT		0
 #define CONFIG_SYS_BAUDRATE_TABLE	{ 9600, 19200, 38400, 57600, 115200 }