virt: acrn: split acrn_mmio_dev_res out of acrn_mmiodev

virt: acrn: split acrn_mmio_dev_res out of acrn_mmiodev

Add struct acrn_mmio_dev_res before struct acrn_mmio_dev.
The former is used in the latter and breaking them up provides
better kernel-doc documentation for the struct members.

Suggested-by: Fei Li <fei1.li@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Fei Li <fei1.li@intel.com>
Link: https://patch.msgid.link/20251028040409.868254-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>