staging: wilc1000: rename WPAPtk of enum KEY_TYPE

This patch renames WPAPtk of enum KEY_TYPE to WPA_PTK
to avoid CamelCase naming convention.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>