Revert "doc: rename register_io_emulation_handler"

This reverts commit 7e0204f.

Author: NanlinXie

doc/developer-guides/hld/hv-cpu-virt.rst

@@ -1104,7 +1104,7 @@ APIs to register its IO/MMIO range:
    * - **API**
      - **Description**
 
-   * - register_pio_emulation_handler
+   * - register_io_emulation_handler
      - register an I/O emulation handler for a hypervisor emulated device
        by specific I/O range
 

doc/developer-guides/hld/hv-io-emulation.rst

@@ -316,7 +316,7 @@ I/O bitmaps and register or unregister I/O handlers:
 .. doxygenfunction:: allow_guest_pio_access
    :project: Project ACRN
 
-.. doxygenfunction:: register_pio_emulation_handler
+.. doxygenfunction:: register_io_emulation_handler
    :project: Project ACRN
 
 .. doxygenfunction:: register_mmio_emulation_handler