litedram: Update to new LiteX/LiteDRAM version

Things have changed a bit in upstream LiteX. LiteDRAM now exposes a
wishbone for the CSRs for example.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

lib/console.c

@@ -120,6 +120,7 @@ int puts(const char *str)
 	return 0;
 }
 
+#ifndef __USE_LIBC
 size_t strlen(const char *s)
 {
 	size_t len = 0;
@@ -129,3 +130,4 @@ size_t strlen(const char *s)
 
 	return len;
 }
+#endif