shell: kconfig: Fix SEGGER_SYSTEMVIEW/SHELL_BACKEND_RTT build issue

RTT_CONSOLE depends on CONSOLE, but SEGGER_SYSTEMVIEW and
SHELL_BACKEND_RTT select RTT_CONSOLE without also selecting CONSOLE.

This leads to a build failure in drivers/console/rtt_console.c (compiled
if RTT_CONSOLE is enabled) unless CONSOLE is enabled some other way.
Symbols like CONFIG_RTT_RETRY_DELAY_MS won't be defined, because they
depend on CONSOLE.

Came up in https://github.com/zephyrproject-rtos/zephyr/pull/21860

. This
fix was verified there.

(Would be nice to get rid of some 'select's in the console subsystem at
some point. This is a quick fix.)

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>