LU-13798 llite: fix LL_SBI_FLAGS array again

LU-13798 llite: fix LL_SBI_FLAGS array again

Errors are still being printed by ll_sbi_flags_seq_show():

  exa6: Revise array LL_SBI_FLAGS to match sbi flags please.

This is because LL_SBI_PARALLEL_DIO is a negative int so downshift
does not clear the high bits.  Make ll_flags unsigned to avoid this.

Move the LL_SBI_SNAPSHOT flag out of the way of other flags.
This is in-memory only, so it doesn't matter what value is used.

Test-Parameters: trivial
Fixes: 00152903a180 ("LU-13798 llite: parallelize direct i/o issuance")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I4b695da74a94d5f204804aa5ab16f83688f7a7f0
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52299