LU-8855 llite: return small device numbers for compat stat()

LU-8855 llite: return small device numbers for compat stat()

The compat_sys_*stat*() syscalls will fail unless the devices majors
and minors are both less than 256. So in ll_getattr_it(), if we are in
32 bit compat mode then coerce the device numbers in to the expected
format.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I1bf13258902e13c76b9ebf3476fd1767712de0b3
Reviewed-on: https://review.whamcloud.com/23877
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>