FROMGIT: erofs: convert all uncompressed cases to iomap

Since tail-packing inline has been supported by iomap now, let's
convert all EROFS uncompressed data I/O to iomap, which is pretty
straight-forward.

Link: https://lore.kernel.org/r/20210805003601.183063-4-hsiangkao@linux.alibaba.com


Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
(cherry picked from commit 64690bbc
 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: I84d309d33a9ec8e443a0d0fcb8d0d0967e6aa101
Signed-off-by: Ryuichiro Chiba <chibar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/4583871


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