CHROMIUM: fs: Introduce passthrough attribute for blk-crypto

Introduce attribute for blk-crypto passthrough. Setting this attribute
will allow files to skip the blk-crypto layer.

BUG=b:376100765, b:376099411
UPSTREAM-TASK=b:391902360
TEST=USE=default_key_stateful, add /mnt/stateful_partition/unencrypted
    1. write to /mnt/stateful_partition/unencrypted/a.txt
    2. filefrag -v a.txt to get extents
    3. hexdump -C -n 100 --skip <extent start> /dev/nvme0n1p1
    4. Validate contents have been passed through

Change-Id: I622696656924da27951c0d6fd1ce9f276e997c1a
Signed-off-by: Sarthak Kukreti <sarthakkukreti@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/6195232


Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Hubert Mazur <hmazur@google.com>