RFC: ANDROID: fs: sdcardfs: Use inode iversion helpers

Upstream commit f02a9ad1 ("fs: handle inode->i_version more efficiently")
converted the inode -> i_version counter to an atomic64_t. So move to using
relevant iversion helper routines for basic operations instead.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>