soc: qcom: restrict L2 accessors to ARM64 build tests

The QCOM_KRYO_L2_ACCESSORS can be compile tested only on ARM64 because
it references asm/sysreg.h present only on ARM64.  Mark the dependency
correct, even though as a non-selectable option it does not have real
effect.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230123202601.1296983-1-krzysztof.kozlowski@linaro.org