Revert "gdb_server : 'R' command replied by OK"

Revert "gdb_server : 'R' command replied by OK"

This reverts commit 1e7e59445287c3389b52903a7cacdb5635248f32.

For some reason the above commit added a reply to the restart command - this is
not required as per the gdb docs.

Newer versions of gdb (7.0 and above) will complain about this reply.

Change-Id: Ieeae3dcf44d798a91dfc6f7348da982c2ce1be31
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/910
Tested-by: jenkins
Reviewed-by: Joel Bodenmann <joel@unormal.org>