x86: fix set_fixmap to use phys_addr_t

Impact: fix kprobes crash on 32-bit with RAM above 4G

Use phys_addr_t for receiving a physical address argument
instead of unsigned long. This allows fixmap to handle
pages higher than 4GB on x86-32.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: systemtap-ml <systemtap@sources.redhat.com>
Cc: Gary Hade <garyhade@us.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <49DE3695.6040800@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>