drm/amdgpu/vcn: Adjust firmware names indentation

This is an incredibly trivial fix, just for the sake of
"aesthetical" organization of the defines. Some were space based,
most were tab based and there was a lack of "alignment", now it's
all the same and aligned.

Cc: James Zhu <James.Zhu@amd.com>
Cc: Lazar Lijo <Lijo.Lazar@amd.com>
Cc: Leo Liu <leo.liu@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Sonny Jiang <sonny.jiang@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NGuilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>