For SMP processors the spin_lock_irqsave is _only_ able to disable interrupt
on a core on which it is executed.

Therefore there may be a situation when other cores raise s3c-hsotg IRQ.
Then there are several places where critical sections can be overwritten.

To protect the above thread, a spin_lock in the interrupt handler has been
added. Due to coherent memory view (especially L1 cache) the spin lock
variable control access to IRQ handler only for one CPU core. In this way
serialization to access this driver is provided and hence several spin_lock_*
routines could be removed from IRQ handler's related functions.

The complete_request_lock function has been removed since all its calls
are performed from interrupt (spin lock protected) context.
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>