JFFS2 locking regression fix.

Commit a491486a introduced a locking
problem in JFFS2 -- we up() the alloc_sem when we weren't previously
holding it. This leads to all kinds of fun behaviour later.

There was a _reason_ for the
	if (1 /* alternative path needs testing */ ||
which the above-mentioned commit removed :)

Discovered and debugged by Giulio Fedel <giulio.fedel@andorsystems.com>

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>