ARM: zynq: Remove secondary_startup() declaration from header

secondary_startup() in the header is not needed at all.
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>

arch/arm/mach-zynq/common.h

@@ -29,7 +29,6 @@ extern void zynq_slcr_cpu_state_write(int cpu, bool die);
 extern u32 zynq_slcr_get_device_id(void);
 
 #ifdef CONFIG_SMP
-extern void secondary_startup(void);
 extern char zynq_secondary_trampoline;
 extern char zynq_secondary_trampoline_jump;
 extern char zynq_secondary_trampoline_end;