intel: Check that we can reserve the zero-offset
intel: Check that we can reserve the zero-offset

commit ff57cee0519d ("ocl20/runtime: take the first 64KB page table
entries") tries to allocate a bo at 0 offset, but failed to take into
account that something may already be allocated there that it is not
allowed to evict (particularly when not using full-ppgtt separation).
Failure to do so causes all execution to subsequentally fail with
"drm_intel_gem_bo_context_exec() failed: Device or resource busy"

Reported-by: Kenneth Johansson <ken@kenjo.org>
Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=98647

Contributor: Chris Wilson <711c73f64afdce07b7e38039a96d2224209e9a6c@chris-wilson.co.uk>
Signed-off-by: Yang Rong <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>
Reviewed-by: Ruiling Song <286a174c1339c6eff91abc41c3a1012c95030c95@intel.com>

wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet