xz: move s->lzma.len = 0 initialization to lzma_reset()

xz: move s->lzma.len = 0 initialization to lzma_reset()

It's a more logical place even if the resetting needs to be done
only once per LZMA2 stream (if lzma_reset() called in the middle
of an LZMA2 stream, .len will already be 0).

Link: https://lore.kernel.org/r/20211010213145.17462-4-xiang@kernel.org
Signed-off-by: Lasse Collin <lasse.collin@tukaani.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Origin: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a98a25408b0e
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>