drm/gma500: return errors from Oaktrail HDMI I2C reads

In the Linux kernel, the following vulnerability has been resolved: drm/gma500: return errors from Oaktrail HDMI I2C reads xfer_read() waits for the HDMI I2C transaction to reach I2C_TRANSACTION_DONE, but it ignores both timeout and signal returns from wait_for_completion_interruptible_timeout(). If the interrupt never advances the transaction state, the loop can wait forever. Return -ETIMEDOUT when the completion wait expires, propagate interrupted waits, and make the I2C master_xfer callback return the first transfer error instead of reporting a successful message count.

Where it's fixed