Staging: hv: Add support for >2 TB LUN in storage driver.

If a LUN larger than 2 TB is attached to a Linux VM on Hyper-V, we currently
report a maximum size of 2 TB. This patch resolves the issue in hv_storvsc.
Thanks to Robert Scheck <robert.scheck@etes.de> for reporting the issue.

Reported-by: Robert Scheck <robert.scheck@etes.de>
Signed-off-by: Mike Sterling <mike.sterling@microsoft.com>
Signed-off-by: K.Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>