ext4: fixup 64-bit divides in 3.0-stable backport of upstream fix

Replace C division operators with div64_u64 for divides introduced in
update to linux kernel version 3.0.72

ext4: use atomic64_t for the per-flexbg free_clusters count

Specific to the 3.0-stable backport of the upstream patch.

Change-Id: If2de7acc4d4210e519bc5940e5ba8ea7bf13567d
Signed-off-by: Todd Poynor <toddpoynor@xxxxxxxxxx>
Bump kernel to 0.297

Change-Id: Iedfe0bd0e19a54798535093f8e8c8c0f28978b49