ShellPkg/ShellProtocol: Return error code while fail parsing cmd-line

ShellPkg/ShellProtocol: Return error code while fail parsing cmd-line

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2395

Errors happened in the arguments parsing is not a critical error.
And it would miss the error status code in the release version of shell.
So replace the ASSERT with returning error status code while fail
parsing command-line in UpdateArgcArgv.

Cc: Ray Ni <ray.ni@intel.com>
Cc: Linson Augustine <linson.augustine@intel.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Signed-off-by: Zhichao Gao <zhichao.gao@intel.com>