ARM: prima2: fix __init section for cpu hotplug

ARM: prima2: fix __init section for cpu hotplug

The code in arch/arm/mach-prima2/headsmp.S is used for
both boot time initialization and for cpu hotplug,
so it must not be discarded after the initial boot
is complete. This replaces the __INIT annotation
with __CPUINIT, and marks the sirfsoc_cpu_die as
__ref to annotate that it correctly uses the sections.

Without this patch, building prima2_defconfig results in:

WARNING: arch/arm/mach-prima2/built-in.o(.cpuinit.text+0x130): Section mismatch in reference from the function sirfsoc_boot_secondary() to the function .init.text:sirfsoc_secondary_startup()
The function __cpuinit sirfsoc_boot_secondary() references
a function __init sirfsoc_secondary_startup().
If sirfsoc_secondary_startup is only used by sirfsoc_boot_secondary then
annotate sirfsoc_secondary_startup with a matching annotation.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Barry Song <baohua.song@csr.com>