arc: emsdp: docs: Prefer Degilent over Opella-XD

Back in the day on early board samples built-in Digilent JTAG probe
was not functional so we used externally attached Ashling Opella-XD
probe. But now with production units everything works as expected and
so we anybody may enjoy readily avaialble built-in JTAG probe so
we specify Digilent oprion on MDB's command line example.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/board/synopsys/emsdp/README b/board/synopsys/emsdp/README
index 034062e..036554c 100644
--- a/board/synopsys/emsdp/README
+++ b/board/synopsys/emsdp/README
@@ -79,5 +79,5 @@
 
       2.1. In case of proprietary MetaWare debugger run:
       ------------------------->8----------------------
-      mdb -dll=opxdarc.so -OK -preloadexec="eval *(int*)0xf0001000=0" u-boot
+      mdb -digilent -OK -preloadexec="eval *(int*)0xf0001000=0" u-boot
       ------------------------->8----------------------