ACPI: FFH: Drop the inclusion of linux/arm-smccc.h

The inclusion of linux/arm-smccc.h in acpi_ffh is unnecessary and can
be even termed wrong. It is needed in the arm64 architecture callback
implementation and probably is the leftover from the missed cleanup of
the initial implementation.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>