drm/amd/display: Use ARRAY_SIZE for array length

Use of macro ARRAY_SIZE to calculate array size minimizes
the redundant code and improves code reusability.

./drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c:164:45-46: WARNING: Use ARRAY_SIZE.
./drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c:183:47-48: WARNING: Use ARRAY_SIZE.
./drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c:237:45-46: WARNING: Use ARRAY_SIZE.
./drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c:257:47-48: WARNING: Use ARRAY_SIZE.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9405


Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>