x86: kexec/i386: fix sparse warnings: Using plain integer as NULL pointer

Fix these sparse warnings:

  arch/x86/kernel/machine_kexec_32.c:124:22: warning: Using plain integer as NULL pointer
  arch/x86/kernel/traps.c:950:24: warning: Using plain integer as NULL pointer
Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Cc: trivial@kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/machine_kexec_32.c

@@ -121,7 +121,7 @@ static void machine_kexec_page_table_set_one(
 static void machine_kexec_prepare_page_tables(struct kimage *image)
 {
 	void *control_page;
-	pmd_t *pmd = 0;
+	pmd_t *pmd = NULL;
 
 	control_page = page_address(image->control_code_page);
 #ifdef CONFIG_X86_PAE

arch/x86/kernel/traps.c

@@ -942,7 +942,7 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_BADSTK;
-	info.si_addr = 0;
+	info.si_addr = NULL;
 	if (notify_die(DIE_TRAP, "iret exception",
 			regs, error_code, 32, SIGILL) == NOTIFY_STOP)
 		return;