ion: add `0x' prefix to hex numbers in debugfs output

Sometimes it's not really clear if you're looking at a base-10 or
base-16 number. Add a `0x' prefix to all hex numbers to alleviate some
confusion.

Change-Id: I7b5438349e000bd7cfa1958cfe91d9e95f39b657
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>