Clarify that systems that have the GPIO pins wired to the hardware volume control need a device resource hint.
Clarify that systems that have the GPIO pins wired to the hardware
volume control need a device resource hint.

Reviewed by:	scottl

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase