ANDROID: fuse-bpf: Make inodes with backing_fd reachable

for regular FUSE fuse_iget

Currently, when we’re trying to find inode based on their
backing inode we strictly checking on nodeid == 0, so
basically we’re not supporting nodeid != 0 for inode,
which is backed by another one. Alongside with this, we’re
using backing_inode as a hash for inode which make this inode
not reachable for regular FUSE fuse_iget that as a result
causing backing_inode losing because instead of getting
existent one (with backing inode) we create a new one as
a part of readdirplus.

For more details please check: go/fuse-loosing-inode-with-backing

Bug: 219958836
Test: Manually checked that /data and /obb inodes
always have inode numbers configured.
Co-developed-by: Paul Lawrence <paullawrence@google.com>

Change-Id: If6a5fb340561ac6320d3c4e86215f1bcd4c2c10c
Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>