system: images: rock-4c-plus: remove duplicated serial port service.

Without this change, the rock-4c-plus boots fine and we can see the serial
port output is fine, but only part of what is typed through the serial port
reaches the console. This makes it very difficult to type commands.

And with this change, the serial port is already activated automatically and
in that case we can interact well with the console.

* gnu/system/images/rock-4c-plus.scm (rock-4c-plus-barebones-os):
  remove serial port service.

Change-Id: Ieb87f2ed6054b529ffa4399fcf4ec997e3e454a6
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
Signed-off-by: Vagrant Cascadian <vagrant@debian.org>

gnu/system/images/rock-4c-plus.scm

@@ -50,15 +50,6 @@
                           (type "ext4"))
                         %base-file-systems))
     (services (append (list
-                       (service
-                        agetty-service-type
-                        (agetty-configuration
-                          (extra-options '("-L")) ;no carrier detect
-                          ;; Upstream u-boot uses 1500000 as well, so the
-                          ;; u-boot-rock-4c-plus-rk3399 inherit it too.
-                          (baud-rate "1500000")
-                          (term "vt100")
-                          (tty "ttyS2")))
                        (service dhcpcd-service-type))
                       %base-services))))