ARM: zynq: Support smp in thumb mode

Add .arm directive to headsmp.S to ensure that the
CPU starts in 32-bit ARM mode and the correct code
size is copied on smp bring-up.
This is related to the fix applied to SoCFPGA by
commit 5616f367
("ARM: SoCFPGA: Fix secondary CPU startup in thumb2 kernel")

Additionally, start secondary CPUs on secondary_startup_arm
to automatically switch from ARM to thumb on a thumb kernel
Signed-off-by: Luis Araneda <luaraneda@gmail.com>
Suggested-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/mach-zynq/headsmp.S

@@ -7,6 +7,8 @@
 #include <linux/init.h>
 #include <asm/assembler.h>
 
+	.arm
+
 ENTRY(zynq_secondary_trampoline)
 ARM_BE8(setend	be)				@ ensure we are in BE8 mode
 	ldr	r0, zynq_secondary_trampoline_jump

arch/arm/mach-zynq/platsmp.c

@@ -81,7 +81,7 @@ EXPORT_SYMBOL(zynq_cpun_start);
 
 static int zynq_boot_secondary(unsigned int cpu, struct task_struct *idle)
 {
-	return zynq_cpun_start(__pa_symbol(secondary_startup), cpu);
+	return zynq_cpun_start(__pa_symbol(secondary_startup_arm), cpu);
 }
 
 /*