Staging: lustre: Add function prototypes in console.h

Sparse reported the following warnings:
warning: symbol 'lstcon_console_init' was not declared. Should it be static?
warning: symbol 'lstcon_console_fini' was not declared. Should it be static?
warning: symbol 'lstcon_ioctl_entry' was not declared. Should it be static?

However since these functions are used in other files,
they cannot be made static, so add protoypes for the same in console.h.

Signed-off-by: Darshana Padmadas <darshanapadmadas@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>