amarisoft/callbox: raise low MTU to 1400

1300 seems to be causing problems with connectivity but 1400 works OK.

BUG=None
TEST=cellular.MTU.low_mtu and cellular.MTU.low_mtu_modb_no_override

Change-Id: Ifafe3aee65c4702ec7f9c2235280712d606aaa93
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/4743770
Reviewed-by: Andrew Lassalle <[email protected]>
Tested-by: Eric Caruso <[email protected]>
Commit-Queue: Eric Caruso <[email protected]>
1 file changed