FmpDevicePkg: Clarify return status of FMP Protocol GetImage()

Clarifed the return status of EFI_FIRMWARE_MANAGEMENT_PROTOCOL.GetImage().
As intended in UEFI 2.10 Specification.

Signed-off-by: Sachin Ganesh <sachinganesh@ami.com>

Author: sachinami

FmpDevicePkg/FmpDxe/FmpDxe.c

@@ -559,7 +559,10 @@ GetTheImageInfo (
   @retval EFI_INVALID_PARAMETER  The Image was NULL.
   @retval EFI_NOT_FOUND          The current image is not copied to the buffer.
   @retval EFI_UNSUPPORTED        The operation is not supported.
-  @retval EFI_SECURITY_VIOLATION The operation could not be performed due to an authentication failure.
+  @retval EFI_SECURITY_VIOLATION The operation could not be completed due to an image corruption.
+                                 If the image is able to be read, the Image buffer will be updated
+                                 with the retrieved image contents.
+  @retval EFI_DEVICE_ERROR       The image could not be read.
 
 **/
 EFI_STATUS