[PATCH 2/2] MdeModulePkg: Minor update to the Data parameter for PEI GetVariable()

[Star Zeng <star.zeng@intel.com>]

PI 1.5 spec has minor update to the Data parameter for PEI
GetVariable(), and no real functional behavior change.

The modifier of Data parameter:
OUT VOID *Data
->
OUT VOID *Data OPTIONAL

The comments of Data parameter:
Data    Points to the buffer which will hold the returned variable value.
->
Data    Points to the buffer which will hold the returned variable value.
        May be NULL with a zero DataSize in order to determine the size of the buffer needed.

The patch is to follow the spec to update the implementation.

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
---
 MdeModulePkg/Universal/Variable/Pei/Variable.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Universal/Variable/Pei/Variable.c b/MdeModulePkg/Universal/Variable/Pei/Variable.c
index a072c31e60e7..4060f4711dd0 100644
--- a/MdeModulePkg/Universal/Variable/Pei/Variable.c
+++ b/MdeModulePkg/Universal/Variable/Pei/Variable.c
@@ -947,9 +947,10 @@ FindVariable (
   @param  DataSize              On entry, points to the size in bytes of the Data buffer.
                                 On return, points to the size of the data returned in Data.
   @param  Data                  Points to the buffer which will hold the returned variable value.
+                                May be NULL with a zero DataSize in order to determine the size of the buffer needed.
 
   @retval EFI_SUCCESS           The variable was read successfully.
-  @retval EFI_NOT_FOUND         The variable could not be found.
+  @retval EFI_NOT_FOUND         The variable was be found.
   @retval EFI_BUFFER_TOO_SMALL  The DataSize is too small for the resulting data.
                                 DataSize is updated with the size required for
                                 the specified variable.
@@ -965,7 +966,7 @@ PeiGetVariable (
   IN CONST  EFI_GUID                        *VariableGuid,
   OUT       UINT32                          *Attributes,
   IN OUT    UINTN                           *DataSize,
-  OUT       VOID                            *Data
+  OUT       VOID                            *Data OPTIONAL
   )
 {
   VARIABLE_POINTER_TRACK  Variable;
-- 
2.7.0.windows.1