[PATCH] USB: cleanup of usblp

this fixes
-potential hang by disconnecting through usbfs
-kzalloc
-general cleanup
-micro optimisation in interrupt handlers

It compiles and I am printing.

Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>