Staging: hv: Rename hv_utils.c to hv_util.c

The hv_utils module will be composed of more than one file;
rename hv_utils.c to accommodate this without changing the module name.

Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: K. Y. Srinivasan <ksrinivasan@novell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>