mfd: tc3589x: Use simple irqdomain

This fixes a regression in the TC3589x driver introduced in
commit 15e27b10
"mfd: Provide the tc3589x with its own IRQ domain"

If a system with a TC3589x expander is booted and a base
IRQ is passed from platform data, a legacy domain will
be used. However, since the Ux500 is now switched to use
SPARSE_IRQ, no descriptors get allocated on-the-fly,
and we get a crash.

Fix this by switching to using the simple irqdomain that
will handle this uniformly and also allocates descriptors
explicitly.

Also fix two small whitespace errors in the vicinity while
we're at it.

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