certs/blacklist: fix const confusion

Fixes commit 2be04df5 ("certs/blacklist_nohashes.c: fix const confusion
in certs blacklist")
Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

certs/blacklist.h

 #include <linux/kernel.h>
 
-extern const char __initdata *const blacklist_hashes[];
+extern const char __initconst *const blacklist_hashes[];