anv/cmd_buffer: Don't call set_subpass in a secondary

anv/cmd_buffer: Don't call set_subpass in a secondary

Initially, we had intended set_subpass to be an interesting function that
did whatever (presumably a lot) setup we needed for a subpass.  In reality,
it just sets a pointer and a dirty bit and then emits depth and stencil
state.  When we call BeginCommandBuffer on a secondary, there's no point in
setting depth and stencil state since it will already be set by the
primary.  Instead, the only thing we need to do at the start of a secondary
is set the subpass pointer and the dirty bit.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>