lib/vsprintf: Less restrictive hashed pointer printing

Commit ad67b74d ("printk: hash addresses printed with %p") and
Commit ef0010a3 ("vsprintf: don't use 'restricted_pointer()'
when not restricting") effectively removed the ability to display
kernel addresses in the kernel log. While this may be a useful feature
in production builds, it is undesirable when trying to debug.

%px is not a possible alternative, because it is unable to differentiate
between a debug and production build.

Change-Id: I139fae7b8488936d214efdd2b5b807fa1c005467
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>