staging: unisys: remove reference of visorutil

commit 53490b545c ("staging: unisys: move periodic_work.c into the visorbus directory")
has removed the visorutil directory but missed removing the reference in
the Makefile.

Fixes: 53490b545c ("staging: unisys: move periodic_work.c into the visorbus directory")
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visorbus/Makefile

@@ -10,4 +10,3 @@ visorbus-y += visorchipset.o
 visorbus-y += periodic_work.o
 
 ccflags-y += -Idrivers/staging/unisys/include
-ccflags-y += -Idrivers/staging/unisys/visorutil