MdeModulePkg: Fix a performance data buffer overrun issue

MdeModulePkg: Fix a performance data buffer overrun issue

The mBmPerfHeader.Count isn't reset to 0 in BmWriteBootToOsPerformanceData()
so when the actual performance data entry count exceeds the LimitCount,
the performance data collection breaks on condition
if (mBmPerfHeader.Count == LimitCount), but 2nd time calling this function
will not break on condition if (mBmPerfHeader.Count == LimitCount) because
the mBmPerfHeader.Count always bigger than LimitCount, which results buffer
overrun.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18417 6f19259b-4bc3-4df7-8a09-765794883524