nine: return GetAvailableTextureMem in bytes as expected (v2)

PIPE_CAP_VIDEO_MEMORY returns the amount of video memory in megabytes,
so need to converted it to bytes.

Fixed Warframe memory detection.

v2: also prepare for cards with more than 4GB memory

Cc: "10.4" <mesa-stable@lists.freedesktop.org>
Tested-by: Yaroslav Andrusyak <pontostoy@gmail.com>
Reviewed-by: Axel Davy <axel.davy@ens.fr>
Signed-off-by: David Heidelberg <david@ixit.cz>
nine: fix wrong variable reset

Error detected by Coverity (COPY_PAST_ERROR)

Cc: "10.4" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Axel Davy <axel.davy@ens.fr>
Signed-off-by: David Heidelberg <david@ixit.cz>
nine: remove unused pipe_viewport_state::translate[3] and scale[3]

2efabd9f5a711a7f6cd1846630244b7814bf25b3 removed them as unused.

This caused random memory overwrites (reported by Coverity).

Cc: "10.4" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Axel Davy <axel.davy@ens.fr>
Signed-off-by: David Heidelberg <david@ixit.cz>
nine: Fix setting of the shift modifier in nine_shader

It is an sint_4, but it was stored in a uint_8...
The code using it was acting as if it was signed.

Problem found thanks to Coverity

Cc: "10.4" <mesa-stable@lists.freedesktop.org>
Tested-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Axel Davy <axel.davy@ens.fr>