sh: sh7757lcr: Fix copy-paste error in README

Update the README to use the correct defconfig.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Chris Brandt <chris.brandt@renesas.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
diff --git a/board/renesas/sh7757lcr/README.sh7757lcr b/board/renesas/sh7757lcr/README.sh7757lcr
index 3e9c1c1..9453839 100644
--- a/board/renesas/sh7757lcr/README.sh7757lcr
+++ b/board/renesas/sh7757lcr/README.sh7757lcr
@@ -20,7 +20,7 @@
 
 You can select the configuration as follows:
 
- - make sh7785lcr_config
+ - make sh7757lcr_config
 
 
 This board specific command: