[PATCH] uml: fix a couple of warnings

Eliminate an unused variable warning in ptrace.c and a size mismatch warning
by adding a cast to __pa.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>