OvmfPkg: Fix spelling mistake for occurred

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2361

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Guomin Jiang <guomin.jiang@intel.com>

OvmfPkg/Bhyve/BhyveRfbDxe/GopScreen.c

@@ -226,7 +226,7 @@ EmuGopSetMode (
 
   @retval EFI_SUCCESS           The Blt operation completed.
   @retval EFI_INVALID_PARAMETER BltOperation is not valid.
-  @retval EFI_DEVICE_ERROR      A hardware error occured writting to the video buffer.
+  @retval EFI_DEVICE_ERROR      A hardware error occurred writting to the video buffer.
 
 **/
 EFI_STATUS

OvmfPkg/Include/Protocol/Legacy8259.h

@@ -58,7 +58,7 @@ typedef enum {
   @param  SlaveBase             The base vector for the Slave PIC in the 8259 controller.
 
   @retval EFI_SUCCESS           The new bases were programmed.
-  @retval EFI_DEVICE_ERROR      A device error occured programming the vector bases.
+  @retval EFI_DEVICE_ERROR      A device error occurred programming the vector bases.
 
 **/
 typedef

OvmfPkg/SioBusDxe/SioService.c

@@ -265,7 +265,7 @@ SioModify (
   @param[in] DeviceIndex       Index of the device supported by this driver.
 
   @retval EFI_SUCCESS          The child device has been created successfully.
-  @retval Others               Error occured during the child device creation.
+  @retval Others               Error occurred during the child device creation.
 
 **/
 EFI_STATUS