mhi: core: always setup/teardown irq during power on/off transitions

It's possible for MHI control driver to call mhi de-init after
PCIe link is off. During free_irq() call, unclock register access
could happens since link is off. Teardown interrupts immediately
after MHI shutdown before de-init call.

CRs-Fixed: 2418657
Change-Id: Ic44f4f897273f13293dd2306bb7f5d9d905a1baf
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>