[MIPS] Alchemy: don't unmask timer IRQ early

Defer the unmasking of the count/compare interrupt (IRQ5) till the
clockevent driver initialization:

- only enable the cascaded IRQs 0 thru 4 in arch_init_irq(); kill the
  ALLINTS macro -- this change is blessed by AMD as I saw it in their own
  patch; :-)

- do not force IRQ5 enabled in plat_time_init() if PM is enabled and there's
  no 32 KHz crystal.

Update the copyrights (taking into account my prior changes), also removing
Pete Popov's old email...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>