soc: nxp_rw6xx: Add support for XTAL32K clock

This clock is used for certain peripherals such
as RTC.
On certain RW612 boards such as rd_rw612_bga, XTAL32K
and ENET share pins. Add code to check if ENET and
XTAL32 are enabled at the same time.

Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>