pan/midgard: Analyze simple loads/store

pan/midgard: Analyze simple loads/store

For shaders using exclusively direct attribute/varyings, we can work
this out statically. For shaders with indirect access, we just set an
upper bound of 16 (the max attributes/varyings we support) and the
actual count will be reported regardless.

We proceed similarly for textures/samplers, as well as for UBOs. While
UBOs can be *indexed* indirectly, the *UBO itself* -- which is what we
count in the shader descriptor (rather than the UBO descriptors) -- is
statically determinable.

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