anv: Silence compiler warnings about uninitialized bind_offset.

anv: Silence compiler warnings about uninitialized bind_offset.

This is a legitimate warning: if anv's blorp_alloc_binding_table() throws
an error from anv_cmd_buffer_alloc_blorp_binding_table(), we silently
continue to use this undefined value.  The rest of this code doesn't seem
very allocation-error-proof, though, either.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>