x86 realmode: Use x86emu register file + defines

By using the (global) register file as defined by x86emu,
we can use the same register access for YABEL and realmode
interrupt handlers.

- the x86 realmode interrupt handlers changed in signature
- to access registers, use X86_$REGNAME now (eg. X86_EAX)
- x86_exception_handler still uses struct eregs *regs to
  avoid spilling the x86emu register file stuff everywhere

Coccinelle script that handled most of this commit:
  @ inthandler @
  identifier FUNC, regs;
  @@
  int FUNC(
  -struct eregs *regs
  +void
   )
  { ... }

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->eax
  +X86_EAX

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->ebx
  +X86_EBX

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->ecx
  +X86_ECX

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->edx
  +X86_EDX

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->esi
  +X86_ESI

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->edi
  +X86_EDI

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->eflags
  +X86_EFLAGS

  @ depends on inthandler @
  identifier regs;
  @@
  -regs->vector
  +M.x86.intno

Change-Id: I60cc2c36646fe4b7f97457b1e297e3df086daa36
Signed-off-by: Patrick Georgi <patrick.georgi@secunet.com>
Reviewed-on: http://review.coreboot.org/1891
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/src/devices/oprom/realmode/x86.h b/src/devices/oprom/realmode/x86.h
index 40c5778..7dfa60f 100644
--- a/src/devices/oprom/realmode/x86.h
+++ b/src/devices/oprom/realmode/x86.h
@@ -42,8 +42,8 @@
 #define INITIAL_EBDA_SEGMENT 0xF600
 #define INITIAL_EBDA_SIZE 0x400
 
-int int10_handler(struct eregs *regs);
-int int12_handler(struct eregs *regs);
-int int16_handler(struct eregs *regs);
-int int1a_handler(struct eregs *regs);
+int int10_handler(void);
+int int12_handler(void);
+int int16_handler(void);
+int int1a_handler(void);