pbl: use "wait" command instead of "flush" command

PBL flush command is restricted to CCSR memory space. So use WAIT
PBI command to provide enough time for data to get flush in
target memory.

Signed-off-by: Zhao Qiang <qiang.zhao@nxp.com>
[York Sun: rewrap commit message]
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/board/freescale/t208xrdb/t2080_pbi.cfg b/board/freescale/t208xrdb/t2080_pbi.cfg
index e200d92..43be8a8 100644
--- a/board/freescale/t208xrdb/t2080_pbi.cfg
+++ b/board/freescale/t208xrdb/t2080_pbi.cfg
@@ -37,5 +37,4 @@
 09000014 ff000000
 09000018 81000000
 #Flush PBL data
-09138000 00000000
-091380c0 00000000
+091380c0 00100000