TCL/SPEAr: default one DDR chip

Handle default case of single DDR chip
Propagate global variable for multi DDR chip

Change-Id: I315380f91ee7fcc2976437aa5836d88a7964fc9d
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/251
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

tcl/board/spear320cpu.cfg

@@ -34,11 +34,18 @@ if { [info exists BOARD_HAS_SRST] } {
 
 $_TARGETNAME configure -event reset-init { spear320cpu_init }
 
+if { [info exists DDR_CHIPS] } {
+        set _DDR_CHIPS $DDR_CHIPS
+} else {
+        set _DDR_CHIPS 1
+}
+
 proc spear320cpu_init {} {
+	global _DDR_CHIPS
 	reg pc 0xffff0020;	# loop forever
 
 	sp3xx_clock_default
 	sp3xx_common_init
-	sp3xx_ddr_init "mt47h64m16_3_333_cl5_async" $DDR_CHIPS
+	sp3xx_ddr_init "mt47h64m16_3_333_cl5_async" $_DDR_CHIPS
 	sp320_init
 }