kselftests: mm: fix wrong __NR_userfaultfd value

grep -rnIF "#define __NR_userfaultfd"
tools/include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282
arch/x86/include/generated/uapi/asm/unistd_32.h:374:#define
__NR_userfaultfd 374
arch/x86/include/generated/uapi/asm/unistd_64.h:327:#define
__NR_userfaultfd 323
arch/x86/include/generated/uapi/asm/unistd_x32.h:282:#define
__NR_userfaultfd (__X32_SYSCALL_BIT + 323)
arch/arm/include/generated/uapi/asm/unistd-eabi.h:347:#define
__NR_userfaultfd (__NR_SYSCALL_BASE + 388)
arch/arm/include/generated/uapi/asm/unistd-oabi.h:359:#define
__NR_userfaultfd (__NR_SYSCALL_BASE + 388)
include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282

The number is dependent on the architecture. The above data shows that:
x86	374
x86_64	323

The value of __NR_userfaultfd was changed to 282 when asm-generic/unistd.h
was included.  It makes the test to fail every time as the correct number
of this syscall on x86_64 is 323.  Fix the header to asm/unistd.h.

Link: https://lkml.kernel.org/r/20240923053836.3270393-1-usama.anjum@collabora.com
Fixes: a5c6bc59 ("selftests/mm: remove local __NR_* definitions")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/pagemap_ioctl.c

@@ -15,7 +15,7 @@
 #include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <math.h>
-#include <asm-generic/unistd.h>
+#include <asm/unistd.h>
 #include <pthread.h>
 #include <sys/resource.h>
 #include <assert.h>