erofs-utils: sync up z_erofs_get_extent_compressedlen()

Sync up with in-kernel z_erofs_get_extent_compressedlen(), mainly
commit 0852b6ca941e ("erofs: fix 1 lcluster-sized pcluster for big
pcluster").

Link: https://lore.kernel.org/r/20210510072303.4628-5-xiang@kernel.org
Signed-off-by: Gao Xiang <xiang@kernel.org>
1 file changed