drm/amdgpu: Use seq_puts() instead of seq_printf()

For a constant format without additional arguments, use seq_puts()
instead of seq_printf(). Also, it fixes the following warning.

WARNING: Prefer seq_puts to seq_printf

And other style fixes:

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
WARNING: Block comments should align the * on each line

Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>