configs/turris1x: switch to linux 4.19

Switch to 4.19 as we have working patchset for that version. We were
using it up to now but upstream seems to fixed configuration and that
resulted in to again using version from this configuration file so let's
switch it here as well.

configs/turris1x/kernel

-CONFIG_LINUX_4_14=y
+CONFIG_LINUX_4_19=y
 CONFIG_DEFAULT_kmod-ath9k=y
 CONFIG_DEFAULT_kmod-usb2-fsl=y
 CONFIG_PACKAGE_kmod-swconfig=y