Blackfin: add workaround for anomaly 05000171

DESCRIPTION:
The Boot ROM is executed at power up/reset and changes the value of the
SICA_IWR registers from their default reset value of 0xFFFF, but does not
restore them.

WORKAROUND:
User code should not rely on the default value of these registers.  Set
the desired values explicitly.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/cpu/blackfin/initcode.c b/cpu/blackfin/initcode.c
index 3120447..d44c6a6 100644
--- a/cpu/blackfin/initcode.c
+++ b/cpu/blackfin/initcode.c
@@ -356,6 +356,10 @@
 #if ANOMALY_05000432
 		bfin_write_SIC_IWR1(-1);
 #endif
+#if ANOMALY_05000171
+		bfin_write_SICA_IWR0(-1);
+		bfin_write_SICA_IWR1(-1);
+#endif
 	} else {
 		serial_putc('G');