drm/tegra: dc: Omit superfluous error message in tegra_dc_probe()

In the function tegra_dc_probe(), when get irq failed, the function
platform_get_irq() logs an error message, so remove redundant message
here.

Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>