drm/amd/display: Release clck_src memory if clk_src_construct fails

[Why]
Coverity reports RESOURCE_LEAK for some implemenations
of clock_source_create. Do not release memory of clk_src
if contructor fails.

[How]
Free clk_src if contructor fails.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>