IntelFrameworkModulePkg GenericBdsLib: Do not assume perf entry count has no change

IntelFrameworkModulePkg GenericBdsLib: Do not assume perf entry count has no change

Current implementation assumes the performance entry count has no change from
multiple GetPerformanceMeasurement() while loops, it may cause the allocated buffer
for PerfEntriesAsDxeHandle at the first loop to be overflowed if the following loop has
the count changed.

This patch is also to sync the change at
commit R18417 "MdeModulePkg: Fix a performance data buffer overrun issue".

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18562 6f19259b-4bc3-4df7-8a09-765794883524