staging: vc04_services: Remove type and function prototype

The function prototype is for a function that is not even in
the kernel, and hence has been removed.
The type VCHIQ_SHARED_MEM_INFO_T is not used anywhere in the
kernel as well.

Signed-off-by: Gargi Sharma <gs051095@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>