shell: do not alias atomic_t
shell: do not alias atomic_t

Previously, a `uint32_t` was aliased as an `atomic_t`. However,
with #39531, `atomic_t` is now a `long` under the hood, which
is 64-bit on 64-bit platforms.

Fixes #40369

Signed-off-by: Christopher Friedt <76f728c1c3997bf5bfe7e9261eff720c92409a2f@gmail.com>

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