LU-5478 style: get rid of seqno_t and mdsno_t typedefs

seqno_t is u64 and mdsno_t is u32

Change-Id: I68be5077ced8a73a8f7bce93ac058d03ecc64b2e
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: http://review.whamcloud.com/11420
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>