HID: wacom: more appropriate tool type categorization

Recent eraser and pen tools are able to be distinguished
by looking at its least significant nibble.
This modification applies it to wacom_intuos_get_tool_type
function and reduces its code lines.

Signed-off-by: Tatsunosuke Tobita <tatsunosuke.tobita@wacom.com>
Signed-off-by: Tatsunosuke Tobita <tatsunosuke.wacom@gmail.com>
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
Link: https://patch.msgid.link/20240709055729.17158-2-tatsunosuke.wacom@gmail.com


Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>