stdio: constify "name" arg in public api

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/iomux.h b/include/iomux.h
index e38a81e..fcf0f93 100644
--- a/include/iomux.h
+++ b/include/iomux.h
@@ -43,6 +43,6 @@
 
 int iomux_doenv(const int, const char *);
 void iomux_printdevs(const int);
-struct stdio_dev *search_device(int, char *);
+struct stdio_dev *search_device(int, const char *);
 
 #endif /* _IO_MUX_H */