panfrost: fix attribute continuation decoding

panfrost: fix attribute continuation decoding

Because attribute continuations aren't considered whole attributes, we
need to increase the total number of attributes for each continuation
when decoding, otherwise we will end up missing a buffer for every
continuation we have.

Signed-off-by: Italo Nicola <italonicola@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8066>