cpufreq: fix qoriq uniprocessor build

The qoriq-cpufreq driver contains a hack for powerpc to include
asm/smp.h on uniprocessor builds so it can get the hardware CPU
number. On ARM, it does not require this hack, but instead gets
a compile error:

In file included from drivers/cpufreq/qoriq-cpufreq.c:24:0:
arch/arm/include/asm/smp.h:18:3: error: #error "<asm/smp.h> included in non-SMP build"
arch/arm/include/asm/smp.h:21:0: warning: "raw_smp_processor_id" redefined

This adds an #ifdef to mirror the one in its get_cpu_physical_id()
function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 2f249358 ("cpufreq: qoriq: rename the driver")
Cc: Tang Yuantian <Yuantian.Tang@freescale.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>