exec: binfmt_misc: kill the onstack iname[BINPRM_BUF_SIZE] array

exec: binfmt_misc: kill the onstack iname[BINPRM_BUF_SIZE] array

After the previous change "fmt" can't go away, we can kill
iname/iname_addr and use fmt->interpreter.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Kees Cook <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Ben Woodard <[email protected]>
Cc: James Bottomley <[email protected]>
Cc: Jim Foraker <[email protected]>
Cc: <[email protected]>
Cc: Travis Gummels <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>