md: add md_submit_discard_bio() for submitting discard bio

md: add md_submit_discard_bio() for submitting discard bio

BugLink: https://bugs.launchpad.net/bugs/1896578
Move these logic from raid0.c to md.c, so that we can also use it in
raid10.c.

Reviewed-by: Coly Li <colyli@suse.de>
Reviewed-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
(backported from commit 2628089b74d5a64bd0bcb5d247a18f78d7b6f4d0)
[mruffell: change submit_bio_noacct() to generic_make_request()]
Signed-off-by: Matthew Ruffell <matthew.ruffell@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>