mfd: db8500-prcmu: Fix irqdomain usage

mfd: db8500-prcmu: Fix irqdomain usage

This fixes two issues with the DB8500 PRCMU irqdomain:
- You have to state the irq base 0 to get a linear domain
  for the DT case from irq_domain_add_simple()
- The irqdomain was not used to translate the initial irq
  request using irq_create_mapping() making the linear
  case fail as it was lacking a proper descriptor.

I took this opportunity to fix two lines of whitespace
errors in related code as I was anyway messing around with
it.

Cc: stable@kernel.org
Acked-by Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>