move memory_read_from_buffer() from fs.h to string.h

move memory_read_from_buffer() from fs.h to string.h

James Bottomley warns that inclusion of linux/fs.h in a low level
driver was always a danger signal.  This patch moves
memory_read_from_buffer() from fs.h to string.h and fixes includes in
existing memory_read_from_buffer() users.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: James Bottomley <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Zhang Rui <[email protected]>
Cc: Bob Moore <[email protected]>
Cc: Thomas Renninger <[email protected]>
Cc: Len Brown <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>