kmsan: include linux/vmalloc.h

This is needed for the vmap/vunmap declarations:

mm/kmsan/kmsan_test.c:316:9: error: implicit declaration of function 'vmap' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        vbuf = vmap(pages, npages, VM_MAP, PAGE_KERNEL);
               ^
mm/kmsan/kmsan_test.c:316:29: error: use of undeclared identifier 'VM_MAP'
        vbuf = vmap(pages, npages, VM_MAP, PAGE_KERNEL);
                                   ^
mm/kmsan/kmsan_test.c:322:3: error: implicit declaration of function 'vunmap' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
                vunmap(vbuf);
                ^

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 8ed691b ("kmsan: add tests for KMSAN")
Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

mm/kmsan/kmsan_test.c

@@ -22,6 +22,7 @@
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/tracepoint.h>
+#include <linux/vmalloc.h>
 #include <trace/events/printk.h>
 
 static DEFINE_PER_CPU(int, per_cpu_var);