Add support for i.MXRT1050's uart.

Cc: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: NJesse Taube <Mr.Bossman075@gmail.com>
Link: https://lore.kernel.org/r/20211215220538.4180616-8-Mr.Bossman075@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>