FROMLIST: BACKPORT: procfs/dmabuf: Add inode number to /proc/*/fdinfo

And 'inode_no' field to /proc/<pid>/fdinfo/<FD> and
/proc/<pid>/task/<tid>/fdinfo/<FD>.

The inode numbers can be used to uniquely identify DMA buffers
in user space and avoids a dependency on /proc/<pid>/fd/* when
accounting per-process DMA buffer sizes.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>

[Kalesh Singh - Resolve conflict in fd/proc/fd.c]
Bug: 159126739
Bug: 167141117
Link: https://lore.kernel.org/lkml/20210208155315.1367371-2-kaleshsingh@google.com/

Change-Id: Ic9c551998832129051ada07374ed02da3248dc9c