selftests/vm: fix display of page size in map_hugetlb

The displayed size is in bytes while the text says it is in kB.

Shift it by 10 to really display kBytes.

Fixes: fa7b9a80

 ("tools/selftest/vm: allow choosing mem size and page size in map_hugetlb")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/e27481224564a93d14106e750de31189deaa8bc8.1598861977.git.christophe.leroy@csgroup.eu
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>