shell: fs: add dependency on kernel allocator
shell: fs: add dependency on kernel allocator

Fix k_malloc linkage error, when filesystem shell is selected,
but no heap allocator is enabled.

Signed-off-by: Pavel Kral <dbcc8f8289ea7748ef3e2d49ba0fc4b3403d93d2@omsquare.com>

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