USB: serial: pl2303: fix the upper baud rate limit check for type_0/1 chips

Fixes the following regression that has been introduced recently with
commit b2d6d98f

:
With type_0 and type_1 chips
- all baud rates < 1228800 baud are rounded up to 1228800 baud
- the device silently runs at 9600 baud for all baud rates > 1228800
  baud

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>