[PATCH] drm: selftests: Fix a typo in test-drm_mm.c

[Chris Wilson]

Quoting Masanari Iida (2019-08-19 14:05:52)
> This patch fix a spelling typo in test-drm_mm.c
> 
> Signed-off-by: Masanari Iida <standby24x7 at gmail.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris