module: check kernel param length at compile time, not runtime

The kparam code tries to handle over-length parameter prefixes at
runtime.  Not only would I bet this has never been tested, it's not
clear that truncating names is a good idea either.

So let's check at compile time.  We need to move the #define to
moduleparam.h to do this, though.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/include/linux/module.h b/include/linux/module.h
index eddf27d..196b499 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -29,7 +29,7 @@
 #define MODULE_SYMBOL_PREFIX ""
 #endif
 
-#define MODULE_NAME_LEN (64 - sizeof(unsigned long))
+#define MODULE_NAME_LEN MAX_PARAM_PREFIX_LEN
 
 struct kernel_symbol
 {