submodule: fix style in function definition

submodule: fix style in function definition

The definitions of 'verify_submodule_committish()' and
'print_submodule_summary()' had wrong styling in terms of the asterisk
placement. Amend them.

Also, the warning printed in case of an unexpected file mode printed the
mode in decimal. Print it in octal for enhanced readability.

Reported-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Shourya Shukla <shouryashukla.oo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>