modem: hl7800: use correct timeouts on KTCPSND to avoid internal deadlock

The response of a KTCPSND has two phases. According to documentation by
wireless the timeout is 60 seconds. The fix respects the timeout on the
second phase, too (waiting for OK or errors from modem). Previously only
the first phase used 60 seconds and the second phase used 5 seconds.

Without this fix the hl7800 will lock the tcp stack for the current
socket indefinitely if another socket operation is performed before the
response from the modem is received.

Additionally all timeouts are adjusted to be at least one second longer
as the documented timeout from wireless. This avoids races between the
hl7800 and the driver.

Signed-off-by: Rene Bredlau <git@unrelated.de>