panfrost: Set custom stride for textures when necessary

panfrost: Set custom stride for textures when necessary

From Gallium (and our) perspective, the stride of a BO is arbitrary. For
internal buffers, we can make it something nice, but for imported linear
buffers (e.g. EGL clients), we don't always have that luxury. To cope,
we calculate the expected stride of a texture, compare it to the BO's
actual reported stride, and if they differ, set the latter as a custom
stride.

Fixes rendering of windows not on tile boundaries (noticeable in Weston
with es2gears_wayland, for instance). Also, this should fix stride
issues with bufer reloading.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>