Support IPMI Serial Transport

Support IPMI Serial interface (basic mode) based on Sec 14,
IPMI 2.0 spec. Serial transport tested with meta-evb-arm
platform with socat and ipmitool.

HW transport can be selected by meson configure flasg.

Tested:

1. socat -x pty,raw,echo=0,link=/tmp/ttyHOST2BMC tcp:localhost:5066
2. ipmitool -I serial-basic -D /tmp/ttyHOST2BMC:115200 mc info

    Device ID                 : 0
    Device Revision           : 0
    Firmware Revision         : 2.17
    IPMI Version              : 2.0
    Manufacturer ID           : 0
    Manufacturer Name         : Unknown
    Product ID                : 0 (0x0000)
    Product Name              : Unknown (0x0)
    Device Available          : no
    Provides Device SDRs      : no
    Additional Device Support :
    Aux Firmware Rev Info     :
        0x00
        0x00
        0x00
        0x00

Change-Id: I2a56390022fce7a974ed75ed6a72ad3fffed9bb6
Signed-off-by: John Chung <john.chung@arm.com>
diff --git a/transport/serialbridge/serialbridge@.service.in b/transport/serialbridge/serialbridge@.service.in
new file mode 100644
index 0000000..a7bfd45
--- /dev/null
+++ b/transport/serialbridge/serialbridge@.service.in
@@ -0,0 +1,18 @@
+[Unit]
+Description=Phosphor IPMI Serial DBus Bridge
+StartLimitBurst=3
+StartLimitIntervalSec=300
+After=phosphor-ipmi-host.service
+
+[Service]
+Restart=always
+RestartSec=10
+TimeoutStartSec=60
+TimeoutStopSec=60
+ExecStartPre=/bin/stty -F /dev/"%i" 115200 litout -crtscts -ixon -echo raw
+ExecStart=@BIN@ -d "%i"
+SyslogIdentifier=serialbridged-%i
+
+[Install]
+WantedBy=multi-user.target
+RequiredBy=