Input: HIL - various fixes for HIL drivers

 - mark some structures const or __read_mostly
 - hilkbd.c: fix uninitialized spinlock in HIL keyboard driver
 - hil_mlc.c: use USEC_PER_SEC instead of 1000000
 - hp_sdc: bugfix for request_irq()/free_irq() parameters, this prevented
           multiple load/unload cycles as module

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>