ARM: Add common entry code for system with two VICs

Add a common entry-macro-vic2.S for systems where there are two VICs
so that the machine or platform directories just need to setup the
correct information before including <asm/entry-macro-vic2.S> into
their own entry-macro.S file.

Since this code is from the S3C64XX project, we update the S3C64XX
machine entry code to use this new header.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>