scsi: storvsc: Removing Pre Win8 related logic

The latest storvsc code has already removed the support for windows 7 and
earlier. There is still some code logic remaining which is there to support
pre Windows 8 OS. This patch removes these stale logic.
This patch majorly does three things :

1. Removes vmscsi_size_delta and its logic, as the vmscsi_request struct is
same for all the OS post windows 8 there is no need of delta.
2. Simplify sense_buffer_size logic, as there is single buffer size for
all the post windows 8 OS.
3. Embed the vmscsi_win8_extension structure inside the vmscsi_request,
as there is no separate handling required for different OS.
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1653478022-26621-1-git-send-email-ssengar@linux.microsoft.comSigned-off-by: Wei Liu <wei.liu@kernel.org>