src/install: constify argument of select_inactive_slot_class_member()
src/install: constify argument of select_inactive_slot_class_member()

rootclass is used read-only, thus it should be a const pointer.

Signed-off-by: Enrico Joerns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>

ejoerns/rauc,rauc/rauc,rauc/rauc,rauc/rauc,ejoerns/rauc,jluebbe/rauc,jluebbe/rauc,jluebbe/rauc,ejoerns/rauc