MAINTAINERS: remove Dan Murphy from m_can and tcan4x5x

Dan Murphy's email address at ti.com doesn't work anymore, mails
bounce with:

| 550 Invalid recipient <dmurphy@ti.com> (#5.1.1)

For now remove all CAN related entries of Dan from the Maintainers
file.

Link: https://lore.kernel.org/r/20210228094218.40015-1-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>