armv8: fsl-lsch3: convert CONFIG_TARGET_x to CONFIG_ARCH_x

The clocks are not dependent on the target but only on the SoC.
Therefore, convert the CONFIG_TARGET_x macros to the corresponding
CONFIG_ARCH_x. This will allow other targets to automatically use the
common code. Otherwise every new target would have to add itself to the
"#if defined(CONFIG_TARGET_x) || .." macros.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>