hv/mod_irq: split irq.c into arch/x86/irq.c and common/irq.c

The common irq file is responsible for managing the central
irq_desc data structure and provides the following APIs for
host interrupt handling.
- init_interrupt()
- reserve_irq_num()
- request_irq()
- free_irq()
- set_irq_trigger_mode()
- do_irq()

API prototypes, constant and data structures belonging to common
interrupt handling are all moved into include/common/irq.h.

Conversely, the following arch specific APIs are added which are
called from the common code at various points:
- init_irq_descs_arch()
- setup_irqs_arch()
- init_interrupt_arch()
- free_irq_arch()
- request_irq_arch()
- pre_irq_arch()
- post_irq_arch()

Tracked-On: #5825
Signed-off-by: Peter Fang <peter.fang@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>

hypervisor/Makefile

@@ -225,6 +225,7 @@ HW_C_SRCS += arch/x86/trampoline.c
 HW_S_SRCS += arch/x86/sched.S
 HW_C_SRCS += arch/x86/rdt.c
 HW_C_SRCS += arch/x86/sgx.c
+HW_C_SRCS += common/irq.c
 HW_C_SRCS += common/softirq.c
 HW_C_SRCS += common/schedule.c
 HW_C_SRCS += common/event.c