staging: vchiq_core: Simplify VCHIQ init

Since the ARM side of VCHIQ support only 1 state, we could simplify
the init code. This makes it possible to avoid BUG_ON and a theoretical
overflow of id.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>