MdePkg/BaseCpuLib: Remove assembly for CpuFlushTlb

MdePkg/BaseCpuLib: Remove assembly for CpuFlushTlb

For different compilers, both IA32 and X64 can use
Ia32/CpuFlushTlbGcc.c, which is C code (no inline assembly code).
To simplify, remove other assemly file for CpuFlushTlb,
and rename Ia32/CpuFlushTlbGcc.c to X86CpuFlushTlb.c.

Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Ray Ni <ray.ni@intel.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>