greybus: svc: error out only for smaller payloads received

!= was used in place of <, while comparing expected and actual payload
size. The module may be running a higher version of the protocol and
might have some extra fields (towards the end) in the structure, and the
AP needs to ignore them.

This also updates the print (expected-payload-size <
actual-payload-size), when the size doesn't match for requests received
by the module. This gives more details required for debugging.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>