suspend: add boot timer
The EG25 modem needs at least 2 minutes after indicating 'RDY' to be fully operational. If the modem is suspended before that, calls or texts may not be seen by the userspace. This mostly occurs when a full reboot or poweroff/poweron sequence of the phone is performed.
A new inhibitor lock in block mode is created when the modem is booted and released as soon as 120s are passed after receiving RDY
from the modem over the AT port.