core_param: call these really, really early - fix

USB sets prefix to "", so there's no dot.  We should really be using
core_param for this.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 kernel/params.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/params.c b/kernel/params.c
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -634,7 +634,9 @@ static void __init param_sysfs_builtin(v
 			continue;
 
 		dot = strchr(kp->name, '.');
-		BUG_ON(!dot);
+		/* FIXME: USB code sets prefix to "".  Should use core_param */
+		if (!dot)
+			continue;
 		name_len = dot - kp->name + 1;
 		strlcpy(modname, kp->name, name_len);
 		kernel_add_sysfs_param(modname, kp, name_len);