ANDROID: sdcardfs: fix sdcardfs_destroy_inode for the inode RCU approach

According to the following commits,
fs: icache RCU free inodes
vfs: fix the stupidity with i_dentry in inode destructors

sdcardfs_destroy_inode should be fixed for the fast path safety.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Change-Id: I84f43c599209d23737c7e28b499dd121cb43636d