HVC console is also used by iSeries, so add that to HVC_DRIVER help.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>