tty: serial: msm_geni_serial: Enable IRQ after device becomes active

When the device resumes, IRQ is enabled. When the device resumes manually
i.e. without intervention from runtime PM framework, sometimes ISR gets
triggered as soon as interrupt is enabled. The check in ISR to ensure that
the device is not in suspended state fails. This failure to handle
interrupt leads to interrupt storm.

If the device resumes manually, enable the IRQ after setting the device
to active state.

Change-Id: I61ffd1c39bbeeaa152c2638ce5307ce55a5ed7c5
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>