pico-imx6ul: Select CONFIG_HUSH_PARSER option

Select CONFIG_HUSH_PARSER option in order to fix the following
problem:

Unknown command 'if' - try 'help'
Unknown command 'then' - try 'help'
Unknown command 'else' - try 'help'
Unknown command 'fi' - try 'help'

Reported-by: Daiane Angolini <daiane.angolini@nxp.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Tested-by: Daiane Angolini <daiane.angolini@nxp.com>