dts: arm: Remove peripheral aliases from NXP SoCs

Removes peripheral aliases from all NXP SoCs (Kinetis, LPC, and i.MX),
which are no longer being used after converting their associated drivers
to use DT_INST macros. The watchdog alias remains because it is used by
tests/drivers/watchdog/wdt_basic_api/

Signed-off-by: Maureen Helm <maureen.helm@nxp.com>