RISC-V: QoS: add resctrl interface for CBQRI controllers

Add interface for CBQRI controller drivers to make use of the resctrl
filesystem.

Co-developed-by: Adrien Ricciardi <aricciardi@baylibre.com>
Signed-off-by: Adrien Ricciardi <aricciardi@baylibre.com>
Signed-off-by: Drew Fustini <dfustini@baylibre.com>