test-submodule: remove command line handling for check-name
The 'check-name' subcommand to 'test-tool submodule' is documented as being
able to take a command line argument '<name>'. However, this does not work -
and has never worked - because 'argc > 0' triggers the usage message in
'cmd__submodule_check_name()'. To simplify the helper and avoid future
confusion around proper use of the subcommand, remove any references to
command line arguments for 'check-name' in usage strings and handling in
'check_name()'.
Helped-by: Jeff King <peff@peff.net> Signed-off-by: Victoria Dye <vdye@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>