Fix omap3_dbginit to write to physical memory.

Setting the OMAP3530 DBGEN bit must be done in physical memory, so
update omap3_dbginit callback to use the new 'mww phys' command syntax.

tcl/target/omap3530.cfg

@@ -56,7 +56,7 @@ proc omap3_dbginit {target} {
      # General Cortex A8 debug initialisation
      cortex_a8 dbginit
      # Enable DBGU signal for OMAP353x
-     $target mww 0x5401d030 0x00002000
+     $target mww phys 0x5401d030 0x00002000
 }
 
 # be absolutely certain the JTAG clock will work with the worst-case