ARM: Check for is_smp for tlb_ops and cache_ops boardcast

This should not be needed when running on UP systems.

Additionally we will also get an undefined instruction on ARM cores
without the extended CPUID registers with CONFIG_SMP_ON_UP.

Also, we can now remove the is_smp() test from mmu.c.

Signed-off-by: Tony Lindgren <tony@atomide.com>