drm/amdgpu: make arrays pctl0_data and pctl1_data static

The arrays pctl0_data and pctl1_data do not need to be in global scope,
so them both static.

Cleans up sparse warnings:
symbol 'pctl0_data' was not declared. Should it be static?
symbol 'pctl1_data' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>