mds/CDir.cc: init some integer vars of C_IO_Dir_OMAP_Fetched in ctor

mds/CDir.cc: init some integer vars of C_IO_Dir_OMAP_Fetched in ctor

Fix for:

CID 1238901 (#1 of 1): Uninitialized scalar field (UNINIT_CTOR)
 uninit_member: Non-static class member ret1 is not initialized in
  this constructor nor in any functions that it calls.
 uninit_member: Non-static class member ret2 is not initialized in
  this constructor nor in any functions that it calls.
 uninit_member: Non-static class member ret3 is not initialized in
  this constructor nor in any functions that it calls.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>