net: wwan: iosm: Let PCI core handle PCI power transition

pci_pm_suspend_noirq() and pci_pm_resume_noirq() already handle power
transition for system-wide suspend and resume, so it's not necessary to
do it in the driver.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>