ARM: 9074/1: ptdump: convert to DEFINE_SHOW_ATTRIBUTE

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>