MdePkg: Add LoongArch Cpucfg function

Add LoongArch AsmCpucfg function and Cpucfg definitions.

Also added Include/Register/LoongArch64/Cpucfg.h to IgnoreFiles of
EccCheck.

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4584

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Signed-off-by: Chao Li <lichao@loongson.cn>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdePkg/Include/Library/BaseLib.h

@@ -327,6 +327,18 @@ DisableLocalInterrupts (
   IN UINT16
   );
 
+/**
+  Read CPUCFG register.
+
+  @param  Index  Specifies the register number of the CPUCFG to read the data.
+  @param  Data   A pointer to the variable used to store the CPUCFG register value.
+**/
+VOID
+AsmCpucfg (
+  IN  UINT32  Index,
+  OUT UINT32  *Data
+  );
+
 #endif // defined (MDE_CPU_LOONGARCH64)
 
 //