VMCI: Remove dependency on BLOCK I/O

No need to bring in dm-mapper.h and along with it a dependency on BLOCK I/O
just to use dm_div_up().  Just use the existing DIV_ROUND_UP().

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andy King <acking@vmware.com>
Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>