ArmPkg/Library: fix: Incorrect SectionLength Calculation.

Ref:[059332b]
Rootcause:  The SectionLength was incorrectly computed using
the FFS_FILE_SIZE() macro. This macro operates on the
EFI_FFS_FILE_HEADER structure, which is incompatible with the
SECTION_SIZE header format.
This mismatch introduces a potential defect due to inaccurate
section size calculation.

Solution: To ensure correctness and structural alignment,
SectionLength must be computed using the SECTION_SIZE macro
defined in MdePkg\Include\Pi\PiFirmwareFile.h.
This macro performs size extraction using byte-wise access.

Cc: Sachin Ganesh <[email protected]>
Signed-off-by: Gowtham M <[email protected]>

Author: GowthamM9974

ArmPkg/Library/DebugAgentSymbolsBaseLib/DebugAgentSymbolsBaseLib.c

@@ -196,7 +196,7 @@ GetImageContext (
     // SectionLength is adjusted it is 4 byte aligned.
     // Go to the next section
     //
-    SectionLength = FFS_FILE_SIZE (FfsHeader);
+    SectionLength = SECTION_SIZE (Section);
     SectionLength = GET_OCCUPIED_SIZE (SectionLength, 4);
     ASSERT (SectionLength != 0);
     ParsedLength += SectionLength;