modules: Kconfig.mcux: Remove implicit selection of HAS_CMSIS_CORE

CONFIG_HAS_MCUX is also selected by ARM64 and XTENSA-based cores
which don't have any CMSIS files. As such, it's wrong to implicitly
select CONFIG_HAS_CMSIS_CORE when CONFIG_HAS_MCUX is selected. Since
the ARM32-based cores implicitly select CONFIG_HAS_CMSIS_CORE there's
no point in CONFIG_HAS_MCUX also selecting it too.

The old approach caused config-related warnings
in external projects such as SOF after the introduction of
Commit '8d5ed530' ("modules: remove uncessary source for
external cmsis kconfig"). The warnings were in the form of:
"HAS_CMSIS_CORE (defined at modules/cmsis/Kconfig:7) has
direct dependencies 0 with value n ..."

Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>