staging: vchiq: stop explicitly comparing with zero to catch errors

The vchiq code tends to follow a coding pattern that's not accepted as
per the Linux kernel coding style

We have this:
	if (expression != 0)

We want this:
	if (expression)

We make an exception if the expression refers to a size, in which case
it's accepted for the sake of clarity.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>