mm: zram: fix swapcached issue on Zram Writeback

Afer Zram backing dev setuped, zram will be treated as a ASYNC IO
swap device, no longer SYNC IO device, because WB pages do have IO
operation on swap in, so the optimization on skiping swapcache
for fast swap device will no longer be applyed on such case.

Now we refactor this optimization, skip the swapcache by checking
SYNC IO state on each swap page via ioctl. Reuse ioctl because we
should not break the GKI.

Change-Id: If01167b7ca178370833fc6e02385bb34ef84318a
Signed-off-by: huangzq2 <huangzq2@motorola.com>
Reviewed-on: https://gerrit.mot.com/1897414


SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key
Signed-off-by: UtsavBalar1231 <utsavbalar1231@gmail.com>