clk: samsung: add CONFIG_OF dependency

clk: samsung: add CONFIG_OF dependency

When CONFIG_OF is disabled, build testing on x86 runs into a couple of
objtool warnings from functions that unconditionally call panic() but
have no __noreturn annotation:

vmlinux.o: warning: objtool: exynos3250_cmu_isp_probe+0x17: samsung_cmu_register_one() is missing a __noreturn annotation
vmlinux.o: warning: objtool: exynos7885_cmu_probe+0x16: exynos_arm64_register_cmu() is missing a __noreturn annotation
vmlinux.o: warning: objtool: exynos850_cmu_probe+0x16: exynos_arm64_register_cmu() is missing a __noreturn annotation
vmlinux.o: warning: objtool: exynosautov9_cmu_probe+0x16: exynos_arm64_register_cmu() is missing a __noreturn annotation

The objtool analysis is correct, and this could be addressed by just
returning success whenever CONFIG_OF is disabled to let all that code
be eliminated, but since the driver is no use without CONFIG_OF,
just add that as a dependency. It will still get compile tested on
all architectures since CONFIG_OF is enabled in allmodconfig and most
randconfig builds.

Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230609081559.915867-1-arnd@kernel.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>