drm/amdgpu: don't modify num_doorbells for mes

This patch removes the check and change in num_kernel_doorbells
for MES, which is not being used anywhere by MES code.

V2: Fixed checkpatch warnings.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Christian Koenig <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>