The introduction of __qcom_scm_set_boot_addr_mc() relies on
cpu_logical_map() and MPIDR_AFFINITY_LEVEL() from smp_plat.h, but only
ARM and ARM64 has this include file, so the introduction of this
dependency broke compile testing on e.g. x86_64.

Make the inclusion of smp_plat.h and the affected function depend on
ARM || ARM64 to allow the code to still be compiled.

Fixes: 55845f46 ("firmware: qcom: scm: Add support for MC boot address API")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211025025816.2937465-1-bjorn.andersson@linaro.org