MdeModulePkg/BootMaintManagerUiLib: Declare EFIAPI for ChooseFile handler

The BootMaintenanceManagerUiLib use ChooseFile() from FileExplorerLib
to select files. And the third parameter in ChooseFile() is CHOOSE_HANDLER,
per the definition of CHOOSE_HANDLER, it must use EFIAPI as the calling
convention. But the calling convention was not specified for following
handlers: CreateBootOptionFromFile, CreateDriverOptionFromFile,
BootFromFile. Now specifies the calling convention for those functions.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Gary Lin <glin@suse.com>

MdeModulePkg/Library/BootMaintenanceManagerUiLib/BootMaintenanceManager.h

@@ -1305,6 +1305,7 @@ BootMaintCallback (
 
 **/
 BOOLEAN 
+EFIAPI
 CreateBootOptionFromFile (
   IN EFI_DEVICE_PATH_PROTOCOL    *FilePath
   );
@@ -1318,6 +1319,7 @@ CreateBootOptionFromFile (
   @retval FALSE  Not exit caller function.
 **/
 BOOLEAN 
+EFIAPI
 CreateDriverOptionFromFile (
   IN EFI_DEVICE_PATH_PROTOCOL    *FilePath
   );
@@ -1332,6 +1334,7 @@ CreateDriverOptionFromFile (
   
 **/
 BOOLEAN 
+EFIAPI
 BootFromFile (
   IN EFI_DEVICE_PATH_PROTOCOL    *FilePath
   );

MdeModulePkg/Library/BootMaintenanceManagerUiLib/BootOption.c

@@ -857,6 +857,7 @@ GetDriverOrder (
   @retval FALSE  Not exit caller function.
 **/
 BOOLEAN 
+EFIAPI
 BootFromFile (
   IN EFI_DEVICE_PATH_PROTOCOL    *FilePath
   )
@@ -929,6 +930,7 @@ ReSendForm(
   @retval FALSE  Not exit caller function.
 **/
 BOOLEAN 
+EFIAPI
 CreateBootOptionFromFile (
   IN EFI_DEVICE_PATH_PROTOCOL    *FilePath
   )
@@ -946,6 +948,7 @@ CreateBootOptionFromFile (
 
 **/
 BOOLEAN 
+EFIAPI
 CreateDriverOptionFromFile (
   IN EFI_DEVICE_PATH_PROTOCOL    *FilePath
   )