mvebu: fix missing include of common.h in cpu-reset.c

The mvebu_cpu_reset_deassert() is missing the definition for
it, so include common.h where it is defined to fix the warning:

arch/arm/mach-mvebu/cpu-reset.c:25:5: warning: symbol 'mvebu_cpu_reset_deassert' was not declared. Should it be static?

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>