video: slimport: Fix unblanced IRQ enable

If irq_enabled is set again, it causes the unblanced IRQ enable problem and
slimport would be not working properly. So if irq_enabled is set again,
In order to fix the problem, disable the irq and initialize the flags.

Change-Id: I27ad8ae7d553e515e15dd87744c221dbbb3a0717
Signed-off-by: Devin Kim <dojip.kim@lge.com>