ShellPkg: Add the check of parameter number in "DrvCfg" command

ShellPkg: Add the check of parameter number in "DrvCfg" command

In shell spec, the usage of "Drvcfg" command is: drvcfg [-l XXX] [-c]
[-f <Type>|-v|-s] [DriverHandle [DeviceHandle [ChildHandle]]]
[-i filename] [-o filename]. The parameter number(doesn't include the flags)
cannot exceed 4, now we add this point to check whether using the command
correctly.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-by: Tapan Shah <tapandshah@hpe.com>