i965/fs: Import image access validity checks.

i965/fs: Import image access validity checks.

These utility functions check whether an image access is valid.
According to the spec an invalid image access should have no effect on
the image and yield well-defined results.  Typically the hardware
implements correct bounds and surface checking by itself, but in some
cases (typed atomics on IVB and untyped messages elsewhere) we need to
implement it in software to work around lacking hardware support.

v2: Drop VEC4 suport.
v3: Rebase.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>