arm: nomadik: drop selecting obsolete CLKSRC_NOMADIK_MTU_SCHED_CLOCK

Commit 85b6fcad ("clocksource/drivers/ux500: Drop Ux500 custom
SCHED_CLOCK") removes a sched_clock workaround and its corresponding
config CLKSRC_NOMADIK_MTU_SCHED_CLOCK. Since then, selecting
CLKSRC_NOMADIK_MTU_SCHED_CLOCK in ./arch/arm/mach-nomadik/Kconfig has no
effect and ./scripts/checkkconfigsymbols.py warns:

CLKSRC_NOMADIK_MTU_SCHED_CLOCK
Referencing files: arch/arm/mach-nomadik/Kconfig

Simply drop selecting the obsolete CLKSRC_NOMADIK_MTU_SCHED_CLOCK.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20220410145623.2620380-1-linus.walleij@linaro.org

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>