ANDROID: x86/pci: Use MMIO wrapper to access pci mmcfg

Instead of using asm code, using the mmio read/write wrapper function to
access pci mmcfg so that these accessing can use the PV MMIO method if
this is enabled.

Bug: 391539939
Bug: 353950489
Test: Microdroid works as a protected VM
Upstream-Task: 402758258

Change-Id: I2e81559097dac6e9ddd89d3ee902aacc98b5582e
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Dmytro Maluka <dmaluka@google.com>