lib: Report the error from __gem_create()

We have two style of ioctl wrappers. The principle interface does error
checking on behalf of the caller (to avoid having lots of repetitious
code in each test), and for the few cases where the error is important
for the test, we also expose a double underscore version. Fix up
__gem_create() to follow this pattern and report the negative error code
returned by the kernel.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
4 files changed