ldlinux: Don't lfree() 'kernel' twice

ldlinux: Don't lfree() 'kernel' twice

This lead to serious problems where duplicate free blocks would appear
next to each other on the free list, which created an infinite loop in
the following code,

	for ( fp = head->next_free ; fp != head ; fp = fp->next_free ) {
	    if ( ARENA_SIZE_GET(fp->a.attrs) >= size ) {
		/* Found fit -- allocate out of this block */
		p = __malloc_from_block(fp, size, tag);
		break;
	    }
	}

because fp == fp->next_free, resulting in modules hanging forever at
malloc() call sites.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>