drm/armada: fix leak of crtc structure

[ Upstream commit 33cd3c07a976e11c3c4cc6b0b3db6760ad1590c5 ]

Fix the leak of the CRTC structure in the failure paths of
armada_drm_crtc_create().

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>