soc: swr-mstr: Fix KW issue in swrm_remove

Irq pointer is first freed and then used in
irq_set_trigger_type and set wakeup capable.
This may lead to Null pointer dereference if
irq is NULL. Free irq after using it.

Change-Id: I86339e9995922cc8111f12593eb781226bb07a2a
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>