[PATCH v1] nvme: allow cmb and pmr emulation on same device

[Andrzej Jakowski]

This patch series does following:
 - Fixes problem where CMBS bit was not set in controller capabilities
   register, so support for CMB was not correctly advertised to guest.
   This is resend of patch that has been submitted and reviewed by
   Klaus [1]
 - Introduces BAR4 sharing between MSI-X vectors and CMB. This allows
   to have CMB and PMR emulated on the same device. This extension
   was indicated by Keith [2]

[1]: 
https://lore.kernel.org/qemu-devel/20200408055607.g2ii7gwqbnv6cd3w@apples.localdomain/
[2]: 
https://lore.kernel.org/qemu-devel/20200330165518.GA8234@redsun51.ssa.fujisawa.hgst.com/