Staging: hv: Get rid of the references to the priv element of struct hv_driver in...

In preparation for getting rid of the priv element from struct hv_driver,
get rid of the references to the priv element of struct hv_driver
in blkvsc_drv.c and storvsc.c

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>