[RFC] target: Move bulk_write_memory to arm7_9

[RFC] target: Move bulk_write_memory to arm7_9

The only remaining user is arm7_9 so remove it from the target API and add
it to struct arm7_9_common to support all its variants with minimal
changes. Many of the variants are likely not correct in the cache/mmu
handling when the bulk write is triggered. This patch does nothing to
change that, except for arm946e, where it was easier to do what might be
the right thing.

Change-Id: Ie73ac07507ff0936fefdb90760046cc8810ed182
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1220
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>