armv8/fsl-lsch2: Implement workaround for PIN MUX erratum A010539

Pin mux logic has 2 options in priority order, one is through RCW_SRC
and then through RCW_Fields. In case of QSPI booting, RCW_SRC logic
takes the priority for SPI pads and do not allow RCW_BASE and SPI_EXT
to control the SPI muxing. But actually those are DSPI controller's
pads instead of QSPI controller's, so this workaround allows RCW
fields SPI_BASE and SPI_EXT to control relevant pads muxing.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
[York Sun: Reformatted commit message]
Reviewed-by: York Sun <york.sun@nxp.com>