Convert CONFIG_MCFTMR to Kconfig

This converts the following to Kconfig:
   CONFIG_MCFTMR

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index ae8d26d..7f6e431 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -201,4 +201,7 @@
 source "board/sysam/amcore/Kconfig"
 source "board/sysam/stmark2/Kconfig"
 
+config MCFTMR
+	bool "Use DMA timer"
+
 endmenu