lguest: compile fixes

arch/x86/lguest/boot.c: In function ‘lguest_init_IRQ’:
arch/x86/lguest/boot.c:824: error: macro "__this_cpu_write" requires 2 arguments, but only 1 given
arch/x86/lguest/boot.c:824: error: ‘__this_cpu_write’ undeclared (first use in this function)
arch/x86/lguest/boot.c:824: error: (Each undeclared identifier is reported only once
arch/x86/lguest/boot.c:824: error: for each function it appears in.)

drivers/lguest/x86/core.c: In function ‘copy_in_guest_info’:
drivers/lguest/x86/core.c:94: error: lvalue required as left operand of assignment

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index bd4b591..9f1659c 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -91,7 +91,7 @@
 	 * Guest has changed.
 	 */
 	if (__this_cpu_read(lg_last_cpu) != cpu || cpu->last_pages != pages) {
-		__this_cpu_read(lg_last_cpu) = cpu;
+		__this_cpu_write(lg_last_cpu, cpu);
 		cpu->last_pages = pages;
 		cpu->changed = CHANGED_ALL;
 	}