ShellPkg/UefiShellAcpiViewCommandLib: Remove the variable "Index"

ShellPkg/UefiShellAcpiViewCommandLib: Remove the variable "Index"

In IortParser.c ,the variable Index is set but not used in
function DumpIortNodeNamedComponent. This will cause build failure
when building ShellPkg with GCC.

Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Zhichao Gao <zhichao.gao@intel.com>
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>