x11-wm/sway: unbreak build after 42a49699a75e

../sway/ipc-json.c:898:11: error: enumeration value 'LIBINPUT_CONFIG_ACCEL_PROFILE_CUSTOM' not handled in switch [-Werror,-Wswitch]

switch (libinput_device_config_accel_get_profile(device)) {

^

Reviewed by: jbeich
Approved by: jbeich
Differential Revision: https://reviews.freebsd.org/D39280
Sponsored by: Beckhoff Automation GmbH & Co. KG