x86: let setup_arch call init_apic_mappings for 32bit

instead of calling it from trap_init()

also move init ioapic mapping out of apic_32.c

so 32 bit do same as 64 bit

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/asm-x86/io_apic.h

@@ -186,6 +186,7 @@ extern void ioapic_init_mappings(void);
 #else  /* !CONFIG_X86_IO_APIC */
 #define io_apic_assign_pci_irqs 0
 static const int timer_through_8259 = 0;
+static inline void ioapic_init_mappings(void) { }
 #endif
 
 #endif