ONKEY interrupt is trapped in PMU occasionally on resuming

[matt_hsu]

Hi Andy,

When I did some experiment on reducing suspended current, I found that
the system could not resume occasionally if the power key is pressed.
Then I monitored the IRQ singal from PCF50633 to CPU, it will stay in
LOW when this pheonmenon occurs. Do you have this on your A5?

I try to find some solutions like the following:

- Change the i2c clock as almost 100K
- modify the sequence of registering platform device

But these two approaches could not eliminate this issue. 

So I tried to use i2cdump to read PCF50633 after every suspend/resume
process. This issue would not happen anymore. Obviously, INTs of
PCF50633 are not read & clear indeed as resuming occasionally. 

Do you think we have to check the value we read from INT1~INT5? INT2 is
0xff when this issue occurs, but the EXTON1~EXTON3 is connected to
ground......... 

Any thoughts?

Cheers,

Matt