ARM: qcom: select ARM_CPU_SUSPEND for power management

The qcom spm driver uses cpu_resume_arm(), which is not included
in the kernel in all configurations:

drivers/built-in.o: In function `qcom_cpu_spc':
:(.text+0xbc022): undefined reference to `cpu_suspend'
drivers/built-in.o: In function `qcom_cpuidle_init':
:(.init.text+0x610c): undefined reference to `cpu_resume_arm'

This adds a 'select' Kconfig statement to ensure it's always
enabled.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Andy Gross <agross@codeaurora.org>