greybus: es2: don't assume just one AP bridge

Previously we had only one AP bridge connected to the AP.  We will
now have two.  Now that the have moved the logging related symbols
into the AP device, we can stop assuming there's only on of them.

Specifically, rename symbols like "apb1_*" to be just "apb_*",
because the "1" is no longer meaningful.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>