oxnas: disable legacy PTYs and virtual terminals

Enabling legacy PTYs causes problems with procd-hotplug.
And as this is a headless target, no need to have virtual terminals.
Remove corresponding kernel config options, they are disabled in
generic kernel config.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(cherry picked from commit c881769a55)

target/linux/oxnas/config-4.14

@@ -231,8 +231,6 @@ CONFIG_LEDS_TRIGGER_GPIO=y
 CONFIG_LEDS_TRIGGER_HEARTBEAT=y
 # CONFIG_LEDS_TRIGGER_NETDEV is not set
 CONFIG_LEDS_TRIGGER_ONESHOT=y
-CONFIG_LEGACY_PTYS=y
-CONFIG_LEGACY_PTY_COUNT=256
 CONFIG_LIBFDT=y
 CONFIG_LOCALVERSION_AUTO=y
 CONFIG_LZ4_DECOMPRESS=y
@@ -352,10 +350,6 @@ CONFIG_VFAT_FS=y
 # CONFIG_VFP is not set
 # CONFIG_VLAN_8021Q is not set
 CONFIG_VM_EVENT_COUNTERS=y
-CONFIG_VT=y
-CONFIG_VT_CONSOLE=y
-CONFIG_VT_CONSOLE_SLEEP=y
-# CONFIG_VT_HW_CONSOLE_BINDING is not set
 # CONFIG_WATCHDOG is not set
 # CONFIG_WQ_POWER_EFFICIENT_DEFAULT is not set
 CONFIG_XZ_DEC_ARM=y