drm/amd/display: remove unnecessary conditional operators

Since the variables named is_end_of_payload and hpd_status are already
bool type, the ?: conditional operator is unnecessary any more.

Clean them up here.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Reviewed-by: Simon Ser <contact@emersion.fr>
Signed-off-by: Ye Guojin <ye.guojin@zte.com.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>