Fix bug 7401.

Handle more than one source dir or file list to the initramfs gen scripts.

The Kconfig help for INITRAMFS_SOURCE claims that you can specify multiple
space-separated sources in order to allow unprivileged users to build an
image.  There are two bugs in the current implementation that prevent this
from working.

First, we pass "file1 dir2" to the gen_initramfs_list.sh script, which it
obviously can't open.

Second, gen_initramfs_list.sh -l outputs multiple definitions for
deps_initramfs -- one for each argument.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>