lib/test_printf.c: call wait_for_random_bytes() before plain %p tests

lib/test_printf.c: call wait_for_random_bytes() before plain %p tests

If the test_printf module is loaded before the crng is initialized, the
plain 'p' tests will fail because the printed address will not be hashed
and the buffer will contain '(ptrval)' instead.

This patch adds a call to wait_for_random_bytes() before plain 'p' tests
to make sure the crng is initialized.

Link: http://lkml.kernel.org/r/20180604113708.11554-1-thierry.escande@linaro.org
Signed-off-by: Thierry Escande <thierry.escande@linaro.org>
Acked-by: Tobin C. Harding <me@tobin.cc>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>