drm: drm_crc: fix a kernel-doc markup

A function has a different name between their prototype
and its kernel-doc markup:

	../include/drm/drm_crtc.h:1257: warning: expecting prototype for drm_crtc_alloc_with_planes(). Prototype was for drmm_crtc_alloc_with_planes() instead

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Simon Ser <contact@emersion.fr>
Signed-off-by: Simon Ser <contact@emersion.fr>
Link: https://patchwork.freedesktop.org/patch/msgid/2439fb6713e9b2aa27a81f3269a4b0e8e7dfcd36.1610610937.git.mchehab+huawei@kernel.org