drm/amd: Fix a typo in two different sentences

s/defintion/definition/ .....two different places.

Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>