Revert "module: drop the lock while waiting for module to complete initialization."

This reverts commit 480b02df, since
Rafael reports that it causes occasional kernel paging request faults in
load_module().

Dropping the module lock and re-taking it deep in the call-chain is
definitely not the right thing to do.  That just turns the mutex from a
lock into a "random non-locking data structure" that doesn't actually
protect what it's supposed to protect.

Requested-and-tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Brandon Philips <brandon@ifup.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>