drivers: leds: Fix -Wpointer-to-int-cast.

drivers/leds/leds-qti-flash.c:1787:22: warning: cast to smaller integer type 'u8' (aka 'unsigned char') from 'const void *' [-Wvoid-pointer-to-int-cast]
        led->max_channels = (u8)of_device_get_match_data(&pdev->dev);
                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Change-Id: I377fdb83ccd9822cb78d146de25f42596923a13e