PerformancePkg Dp_App: Fix ASSERT in GetNameFromHandle

PerformancePkg Dp_App: Fix ASSERT in GetNameFromHandle

This commit will resolve the issue brought by r17745.

StrCpyS (mGaugeString, DP_GAUGE_STRING_LENGTH + 1, StringPtr);

The above using of StrCpyS will cause ASSERT if StringPtr is longer than
mGaugeString. Therefore, StrnCpyS is used here to resolve the issue.

Similar scenario is for:
StrCpyS (mGaugeString, DP_GAUGE_STRING_LENGTH + 1, NameString); (twice)

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@17935 6f19259b-4bc3-4df7-8a09-765794883524