PerformancePkg Dp_App: Resolve buffer size mismatch

PerformancePkg Dp_App: Resolve buffer size mismatch

CHAR16 array mGaugeString[DP_GAUGE_STRING_LENGTH + 1] is pass into
function GetShortPdbFileName(). However, in this function it treats the
size of the input buffer as DXE_PERFORMANCE_STRING_SIZE.

Though DXE_PERFORMANCE_STRING_SIZE is smaller than DP_GAUGE_STRING_LENGTH
now, but this manner might introduce a potential risk of buffer overflow.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17746 6f19259b-4bc3-4df7-8a09-765794883524