drm: drm_edid: remove a duplicated kernel-doc declaration

drm: drm_edid: remove a duplicated kernel-doc declaration

It is not possible to create cross-references for duplicated
symbols. While Sphinx always detected it, on Sphinx 3 it
generates warnings like this:

	.../Documentation/gpu/drm-kms-helpers:326: ../drivers/gpu/drm/drm_edid.c:1626: WARNING: Duplicate C declaration, also defined in 'gpu/drm-kms-helpers'.
	Declaration is 'bool drm_edid_are_equal (const struct edid *edid1, const struct edid *edid2)'.

So, get rid of the duplicated kernel-doc markup.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/9310f4074fa9d29cd3ad60684d86d0ace8dab7ae.1603791716.git.mchehab+huawei@kernel.org