ANDROID: x86/tdx: Rename the handle_mmio() to avoid conflict

Since handle_mmio() is a general function name, it can conflit with
other static defined handle_mmio(), like in gvt driver. So Rename it as
a virtual exception specific function.

Bug: 395299836
Test: Boot, verify cpus are de-privileged and run a minimal protected vm.

Change-Id: I8009624596d563985e1cde9658dec732c811a082
Signed-off-by: Shaoqin Huang <shaoqin.huang@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Signed-off-by: Vineeth Pillai <vineethrp@google.com>