MdeModulePkg MemoryProfile.h:two bytes of Reserved[4] as ActionStringOffset

MdeModulePkg MemoryProfile.h:two bytes of Reserved[4] as ActionStringOffset

At 94092aa60341a3e4b1e1ea7c362781b8404ac538, we extended
MEMORY_PROFILE_ALLOC_INFO to add ActionStringOffset and
Reserved2[6] fields, that was not aware the Reserved[4]
field can be reused to have better memory profile database
size efficiency.

With the patch, PcdMemoryProfilePropertyMask|0x3 and
PcdMemoryProfileMemoryType|0xffff, the memory profile
database size can be reduced as below on my sample platform.

UefiMemoryProfileSize - 0x1597A8 -> UefiMemoryProfileSize - 0x12AB28
SmramProfileSize - 0xCF68 -> SmramProfileSize - 0xB8E8

Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>