drm/radeon/cik: fix typo in documentation

Copy-paste typo.

Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/radeon/cik.c

···
 }
 
 /**
- * cik_select_se_sh - select which SE, SH to address
+ * cik_get_rb_disabled - computes the mask of disabled RBs
  *
  * @rdev: radeon_device pointer
  * @max_rb_num: max RBs (render backends) for the asic