drivers: can: document retval for unsupported filter types
drivers: can: document retval for unsupported filter types

Some CAN controllers do not support all filter combinations (standard
11-bit ID filters, extended 29-bit filter, data frame filters, remote
transmission request).

Document the expected return value (-ENOTSUP) for unsupported filter
types/combinations.

Signed-off-by: Henrik Brix Andersen <24a3f13c22635bab658e39fc5f1e63c575328aae@vestas.com>

galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr