ARM: socfpga: fix build error due to secondary_startup

After commit 02b4e275 (ARM: v7 setup function should invalidate L1
cache) the soc specific secondary_startup is removed, causing build
failures:

../arch/arm/mach-socfpga/platsmp.c: In function 'socfpga_a10_boot_secondary':
../arch/arm/mach-socfpga/platsmp.c:66:140: error: 'socfpga_secondary_startup' undeclared (first use in this function)
../arch/arm/mach-socfpga/platsmp.c:66:140: note: each undeclared identifier is reported only once for each function it appears in

To fix, use the generic secondary_startup.

Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

arch/arm/mach-socfpga/platsmp.c

@@ -63,7 +63,7 @@ static int socfpga_a10_boot_secondary(unsigned int cpu, struct task_struct *idle
 		       SOCFPGA_A10_RSTMGR_MODMPURST);
 		memcpy(phys_to_virt(0), &secondary_trampoline, trampoline_size);
 
-		writel(virt_to_phys(socfpga_secondary_startup),
+		writel(virt_to_phys(secondary_startup),
 		       sys_manager_base_addr + (socfpga_cpu1start_addr & 0x00000fff));
 
 		flush_cache_all();