The core md code calls the ->free method which already frees conf.

Fixes: 07f1a685 ("md/raid1: fail run raid1 array when active disk less than one")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240604172607.3185916-3-hch@lst.de