ANDROID: GKI: Add ANDROID_OEM_DATA(1) in struct request to support pre-read feature.

To implement the foreshow list in the kernel, we need to incorporate additional flags into the request. However, the rq_flags field currently has only 5 remaining bits. Considering the potential future usage by Android or upstream, we propose the addition of an OEM data field to prevent conflicts down the line.

Bug: 339338545

Change-Id: I965450a06a365b53ae82d11bd678983c6c286f1a
Signed-off-by: LongPing Wei <weilongping@oppo.com>