FROMGIT: erofs: decouple basic mount options from fs_context

Previously, EROFS mount options are all in the basic types, so
erofs_fs_context can be directly copied with assignment. However,
when the multiple device feature is introduced, it's hard to handle
multiple device information like the other basic mount options.

Let's separate basic mount option usage from fs_context, thus
multiple device information can be handled gracefully then.

No logic changes.

Link: https://lore.kernel.org/r/20211007070224.12833-1-hsiangkao@linux.alibaba.com


Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
(cherry picked from commit 151aac47
 https://android.googlesource.com/kernel/common

 android13-5.10)

BUG=b:273658215
TEST=`tast run $DUT arc.Boot.vm`
TEST=`tast run $DUT arc.Playstore.vm`

Change-Id: I1dcafcea956310e26103e0e75b4ce461562b5d29
Signed-off-by: Ryuichiro Chiba <chibar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/4583882


Reviewed-by: Hikaru Nishida <hikalium@chromium.org>
Reviewed-by: Sean Paul <sean@poorly.run>