ARM: multi_v7_defconfig: Enable ARM SCMI protocol and drivers

Enable the ARM SCMI protocol and the common clock, cpufreq and sensors
drivers. Broadcom STB platforms (ARCH_BRCMSTB) implement SCMI to provide
support for CPU frequency scaling, clock configuration and temperature
and current sensors.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>