init: export name_to_dev_t and mark name argument as const

DM will switch its device lookup code to using name_to_dev_t() so it
must be exported.  Also, the @name argument should be marked const.

Signed-off-by: Dan Ehrenberg <dehrenberg@chromium.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

init/do_mounts.c

@@ -207,7 +207,7 @@ done:
  *	bangs.
  */
 
-dev_t name_to_dev_t(char *name)
+dev_t name_to_dev_t(const char *name)
 {
 	char s[32];
 	char *p;
@@ -286,6 +286,7 @@ fail:
 done:
 	return res;
 }
+EXPORT_SYMBOL_GPL(name_to_dev_t);
 
 static int __init root_dev_setup(char *line)
 {