Similar to the 2400 and 2500, the LPC controller has some simple reset
lines that are used by the UART devices.

This is already documented in LPC bindings document.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20220221072650.129348-1-joel@jms.id.au