serial: sunsu.c - don't explicitly tie array size to dynamic entity

The addition of 8250-like entities continues to grow, while this
driver has a snapshot of a select few common 8250 UARTs.  So it
has no need to grow with the new additions, since it calls out
its own (largely historic) static list which does not grow.

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>