LU-4000 lloop: Fix build failure on ppc64

LU-4000 lloop: Fix build failure on ppc64

On ppc64 with 64k pages, we get a build failure in lloop:

drivers/staging/lustre/lustre/llite/lloop.c:527:2:
note: in expansion of macro 'CLASSERT'
CLASSERT(PAGE_CACHE_SIZE < (1 << (sizeof(unsigned short) * 8)));

There's no need to change the queue's logical block size. Even if it could
accept a 64k value, that would result in any file system on top of it
needing to also use 64k blocks. It'd be safe to set it to 4k, but there's
no actual need for it. It's not used to split requests except for WRITE_SAME,
which lloop doesn't implement anyway.

Change-ID: Ib36959ca2323ab0dfdc1fb34aeffb778cffd6c92
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-on: http://review.whamcloud.com/7745
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>