1. Added ReadWriteBarrier() before and after each I/O read/write function. 2. Removed all ReadWriteBarrier() function calls in all MMIO functions.
1. Added ReadWriteBarrier() before and after each I/O read/write function.
2. Removed all ReadWriteBarrier() function calls in all MMIO functions.

git-svn-id: 5648d1bec6962b0a6d1d1b40eba8cf5cdb62da3d@1224 6f19259b-4bc3-4df7-8a09-765794883524

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2