video: exynos_dp: Reset and initialize DP before requesting irq

If DP is not reset properly before kernel bootup(in bootloader code),
there can be few pending interrupts, and sometimes they invoke
DP irq handler as soon as the irq handler is registered in DP probe.
So, we make the DP driver more robust by resetting and
initializing DP at the earliest and then registering the irq handler.

Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Signed-off-by: Jingoo Han <jg1.han@samsung.com>