fs: rename inode member of struct filep to priv ...

Because that's what it is. 'inode' will become confusing
once we support real inodes.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

move file helper functions to separate file ...

We have our file helper functions in several places. Move them
all to lib/libfile.c.
With this we no longer have file helpers in fs/fs.c which contains
the core fs functions and no functions in lib/libbb.c which are
not from busybox.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Merge branch 'for-next/fs' ...

Conflicts:
	fs/Kconfig
	fs/Makefile

fs: add uimagefs ...

this will provide the image data and information via file

 # ls -l /tmp/
-rwxrwxrwx          3 arch
-rwxrwxrwx         12 compression
-rwxrwxrwx         16 name
-rwxrwxrwx          5 os
-rwxrwxrwx         24 time
-rwxrwxrwx         12 type
-rwxrwxrwx         10 load_addr
-rwxrwxrwx         10 entry_point
-rwxrwxrwx    2199875 data0
-rwxrwxrwx    2199875 data
-rwxrwxrwx         10 data.crc

if it's multi image

 # ls -l /tmp-multi/
-rwxrwxrwx          3 arch
-rwxrwxrwx         12 compression
-rwxrwxrwx         16 name
-rwxrwxrwx          5 os
-rwxrwxrwx         24 time
-rwxrwxrwx         16 type
-rwxrwxrwx         10 load_addr
-rwxrwxrwx         10 entry_point
-rwxrwxrwx       1292 data0
-rwxrwxrwx        983 data1
-rwxrwxrwx       2287 data
-rwxrwxrwx         10 data.crc

you can get the image header via an ioctl on any file
UIMAGEFS_METADATA

if you want to check the crc do

 # crc32 -f /tmp-multi/data -V /tmp-multi/data.crc
CRC32 for /tmp-multi/data 0x00000000 ... 0x000008ee ==> 0x88d5a0db

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>