Broadcast should not be needed when running SMP kernel on UP systems.

Also, this fixes an undefined instruction for SMP_ON_UP on earlier ARM
cores without the extended CPUID_EXT_MMFR3 register.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>